For many years, Microsoft has improved the recovery system of the Windows operating system, and in Windows 7 and Windows Vista it works almost automatically. If you boot from the Windows 7 installation disc and click "" ("Repair Computer"), the Windows Recovery system will start and attempt to repair any errors it finds. It is able to fix a large number of problems, however, it is quite possible that the bootloader is damaged, and the recovery system cannot cope with this problem. In this case, you can restore the bootloader manually using the Bootrec.exe utility.
Appendix bootrec.exe is used to fix errors associated with bootloader damage and, as a result, the inability to start Windows 7 and Windows Vista operating systems.
Sequencing
The utility will display help on the available command line options.
Description of bootrec.exe startup keys
Bootrec.exe /FixMbr- Launched with the /FixMbr switch, the utility writes a Windows 7 and Windows Vista compatible Master Boot Record (MBR) to the system partition. Use this option to troubleshoot problems with master boot record corruption or if you wish to remove non-standard code from it. The existing partition table is not overwritten in this case
Bootrec.exe /FixBoot- Launched with the /FixBoot key, the utility writes a new boot sector compatible with Windows 7 and Windows Vista to the system partition. You need to use this option in the following cases:
- The boot sector of Windows Vista or Windows 7 has been replaced with a non-standard one.
- The boot sector is corrupted.
- A previous version of the Windows operating system was installed after installing Windows Vista or Windows 7. For example, if Windows XP was installed, NTLDR (Windows NT Loader, Windows NT boot loader) will be used, the code for the regular NT 6 boot loader (Bootmgr) will be overwritten by the Windows XP installer .
It should be noted that a similar effect can be achieved using the bootsect.exe utility, also located on the Windows 7 boot media. To do this, you need to run bootsect.exe with the following options:
bootsect /NT60 SYS- The boot sector of the system partition will be overwritten with BOOTMGR compatible code. You can learn more about using the bootsect.exe utility by running it with the /help option.
Bootrec.exe /ScanOs- Launched with key / ScanOs, the utility scans all drives for installed Windows Vista and Windows 7 operating systems. In addition, when using it, a list of found systems is displayed that are not currently registered in the Windows Boot Configuration Data (BCD) Store)
Bootrec.exe /RebuildBcd- Launched with this key, the utility scans all drives for installed Windows Vista or Windows 7 operating systems. Found operating systems are displayed in a list from which they can be added to the Windows Boot Configuration Data Store. Also use this option if you want to completely rebuild the boot configuration data store. Before doing this, you must delete the previous storage. The set of commands in this case can be as follows:
bcdedit /export C:\BCDcfg.bak
attrib -s -h -r c:\boot\bcd
del c:\boot\bcd
bootrec /RebuildBcd
In the example above, the current boot configuration store is exported to a file C:\BCDcfg.bak, the "system", "hidden" and "read-only" attributes are removed from it, after which it is deleted with the DEL command and rebuilt with the command bootrec /RebuildBcd.
Of course utility bootrec.exe very functional, however, it will not help if, for example, the Windows bootmgr file is damaged or physically missing. In this case, you can use another utility, also included in the Windows 7 distribution media - bcdboot.exe.
Restoring the Boot Environment with BCDboot.exe
BCDboot.exe is a tool that is used to create or restore a boot environment located on the active system partition. The utility can also be used to transfer boot files from one hard drive or partition to another.
The command line in this case might look like this:
bcdboot.exe e:\windows
Replace e:\windows to the path that matches your system. This operation will repair the corrupted Windows Boot Environment, including the Boot Configuration Data (BCD) store files, including the file mentioned above bootmgr.
Syntax of bcdboot command-line options
The bcdboot.exe utility uses the following command line options:
BCDBOOT source]
a source- Specifies the location of the Windows directory used as the source when copying boot environment files.
/l- Optional parameter. Specifies the language of the boot environment. The default is English (United States).
/s- Optional parameter. Specifies the drive letter of the system partition where the boot environment files will be installed. The default is the system partition specified by the BIOS firmware.
/v- Optional parameter. Enables the mode of detailed logging of the utility operation.
/m- Optional parameter. Combines the settings of the newly created and existing storage boot record and writes them to the new boot record. If an operating system bootloader GUID is specified, combines the bootloader object with the system template to create a boot entry.
Summary. The article discussed the principles of working with utilities bootrec.exe And bcdboot.exe, which serve to resolve problems associated with the inability to start the Windows 7 operating system due to a damaged or missing bootloader
Or corrupted files (for example: NTLDR is missing. Press Ctrl+Alt+Del to restart, or Cannot start Windows due to corrupted or missing file: \WINDOWS\SYSTEM32\CONFIG\SYSTEM, or Cannot start Windows due to software errors. Report this as a bug: Kernel DLLs required. Report this error to the support team).
At the same time, you can neither go to the restore point, nor load the last known good configuration, nor even boot into . In such cases, most immediately rush to reinstall, although, as a rule, you can restore the system to working capacity in 5 minutes using the so-called recovery console.
For this you need to BIOS install boot from CD-ROM" a, place in a tray CD-ROM" and the boot disk with the installation package Windows XP Professional and reboot. When the installer Windows XP load your files into RAM , a window will appear Installing Windows XP Professional, containing the selection menu from which we are interested in the item *To restore Windows XP using the Recovery Console, click.
Click R . The recovery console will load. If onone is installed, and it is () installed on disk C:, the following message will appear:
1: C:\WINDOWS
Which copy Windows should you sign in?
Enter 1 , click Enter.
A message will appear:
Enter administrator password:
Enter password, click Enter(if there is no password, just click Enter).
The system prompt will appear:
C:\WINDOWS>
enter fixmbr
A message will appear:
**A WARNING**
This computer has a non-standard or invalid master boot record. Using FIXMBR can damage the existing partition table. This will result in the loss of access to all partitions of the current hard drive.
If there are no disk access problems, it is recommended to abort the FIXMBR command.
Are you confirming the writing of the new MBR?
Enter y(which means yes).
A message will appear:
A new MBR is made to the physical disk \Device\Harddisk0\Partition0.
The new master boot record has been successfully created.
At the system prompt that appears: C:\WINDOWS>
Enter fixboot
A message will appear:
Destination partition: C:.
Do you want to write a new boot sector to the C: partition?
Enter y(which means yes).
A message will appear:
The file system on the boot partition is NTFS (or FAT32).
The FIXBOOT command writes a new boot sector.
The new boot sector has been successfully written.
Click Del, sign in BIOS Setup and set to boot from hard drive.
Notes
1. If you don't know what is And recovery console, in such critical situations – to avoid worsening the situation! – don't try to fix it yourself – it is better to seek help from specialists.
2. If on installed more than one , – contact the experts!
3. Brief reference on the commands used:
a) fixboot drivename:
This command is used to write a new boot sector code Windows in the system partition. In command syntax drive_name – disk on which the boot sector will be written. This command fixes corruption in the boot sector Windows. It overrides the settings , which are written to the boot partition of the system. Command fixboot supported on base x86.
b) fixmbr devicename
This command is used to restore the master boot record of a boot partition. In command syntax device_name – optional device name that requires a new master boot record ( MBR). Use this command if the boot record is run Windows fails.
In the case when the device fails to start and errors constantly occur during the download, you should try to use the standard recovery tool. If it did not help or is not available, then you can try to fix the boot entries using the command line. How to do this will be described in this article. This method can help when it does not come to starting the OS itself.
bootrec.exe utility
First of all, the standard system recovery utility will be used, which will have to be called from the console.
Unfortunately, in order to start the console, additional steps are required. Will be necessary create a recovery disk or a disk with a version for installing Windows. It's a good idea to have them always on hand, rather than rush to write them down on another device or with friends.
For the seven, you will need to select the item " System Restore”, and then launch the console. For the G8, the first item will remain unchanged, but then you have to go to diagnostics, from there call Extra options and only then start the console. 
In the window that appears, enter the command bootrec.exe, after which a list of available actions with all the necessary explanations will appear. Each point will be discussed in more detail below.
Write a new boot sector
The second command in this list will allow you to overwrite the current boot sector under the operating system that is currently available. Sector failures can occur for several reasons:
To fix all this, just enter the fixboot command as shown in the picture.
Fixing the MBR
This command, which is the first line, will allow you to correct the corresponding entries on the system hard drive. In fact, they responsible for order booting the system, from which the BIOS learns what to load and in what sequence. This operation can help if error occurrence:
You need to enter the fixmbr command as shown in the picture, and all these problems should disappear.
How to find all installed systems
There may be situations in which not all installed systems are available for boot. Performing the appropriate operation will allow check device for the presence of other installed operating systems, and using the next section of the article, they can be added to this list. The required command is shown in the picture. 
Rebuilding BCD
Entering the corresponding operation /RebuildBcd after the initial command, it will write all found operating systems and recovery tools to the Windows boot configuration file, which will allow them to be displayed at the next boot. 
From the article it is clear that many problems with starting the system can be solved independently, using the command line and just one utility. So it's worth trying this option before you start to panic, rearrange the OS, or take your computer in for repair.
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Installing Windows 2000 Installation Problems
The system boot process can be divided into several stages:
Until the bootloader screen appears (menu for selecting the system you want to boot):
- Immediately after the completion of the self-test phase (POST), the computer freezes
- The bootloader screen does not appear.
- The following types of error messages appear on the screen:
- A disk read error occurred.
- Insert a system diskette and restart the system
- Hard Disk Error.
- Hard Disk Absent/Failed
It is possible that in this scenario the computer will not be able to start at all. If you previously formatted all partitions to use the NTFS file system, you will not be able to use MS-DOS utilities to solve these problems. I advise you to keep Windows 2000 boot disks handy. This type of problem can be caused by the following things:
- Missing system partition on hard drive. Usually occurs when a newly purchased hard drive is configured incorrectly or when it is incorrectly formatted. You can fix this problem using the FDISK utility.
- The master boot record is corrupted. What is it for?
- Reads the partition table located in this disk sector.
- Specifies the location of the partition's boot sector.
- Loads and executes code located in the partition's boot sector.
- Missing operating system.
- Invalid partition table (Invalid partition table).
You can use the Windows 2000 Recovery Console to repair a corrupted MBR. This is done using the Fixmbr command:
fixmbr [device name]
Parameter device_name: The device (disk) to which you want to write the new master boot record. You can use the map command to get the name. The device name might look like this:
\Device\HardDisk0.
The following example writes a new MBR to the above device.
fixmbr\Device\HardDisk0
If no device name is specified, the new MBR will be written to the boot device, which is the drive from which the main system was booted. If an incorrect or non-standard partition table signature is found, a message is displayed asking for confirmation of the write. If the disks are being accessed without failure, the confirmation should be answered in the negative. Writing a new MBR to the system partition can corrupt partition tables, making partitions inaccessible. Partition boot sector corruption is usually characterized by a blue screen and a STOP error with the following content:
INACCESSIBLE_BOOT_DEVICE.
Or the machine "hangs" during the boot process and the screen remains blank. Even if there is no obvious gross damage, the boot sector of the partition may not work correctly. The problem may be that the NTLDR file is corrupted/corrupted, or the boot sector is corrupted. To diagnose the problem, we proceed in the following way: We try to rename the NTLDR file and start Windows 2000 from this hard disk. If the boot sector is OK and the problem is a corrupted bootloader file, the following message will appear:
Couldn't find NTLDR- if the bootloader file is on an NTFS partition
A kernel file is missing from the disk- if the NTLDR bootloader file is on the FAT partition.
Accordingly, it is required to replace the damaged NTLDR file with a working one (either from a boot diskette or from a working machine).
I immediately warn you that the default NTLDR file has the attributes "hidden", "system" and "read-only". If it is on a FAT partition, you can change the attributes from under DOS using the attrib -s -h -r ntldr command. If after replacing the NTLDR file you do not receive such error messages and the machine still does not want to boot, then the boot partition itself is damaged. To eliminate this trouble, you need to load the recovery console (ie, start the installation of Windows 2000 again and after the procedure for copying the installation files to the hard drive is completed, select NOT installation, BUT SYSTEM RECOVERY). After the console is loaded, use the following command:
Writing a new boot sector to the system partition. The fixboot command is only available on the Windows 2000 Recovery Console, which is run from Windows 2000 Setup.
fixboot [disk]
Parameter: the disk to which you want to write the boot sector. By default, the system partition from which the system was booted is used. In the following example, a new boot sector will be written to the system partition of drive D:
Problems that occur after the bootloader is launched, but before the user is logged into the system
The Windows 2000 Resource Kit contains a debug version of Ntdetect.com called Ntdetect.chk. If Ntdetect.com can't detect all the hardware devices you think it should find, you can use the debug version to help isolate the problem. The debug version is installed using the Installd.cmd file, which does the following:
- Renames the default Ntdetect.com.
- Copies Ntdetect.chk to Ntdetect.com.
After performing these operations, you need to restart your computer. When you start the system with the debug version of Ntdetect, information about all detected hardware will appear on the screen. After completing each information screen, you must press the Enter key. When the debug version is no longer needed, run the installd /not command.
The SOS setting in the Boot.ini file.
You can add the /sos option to the Boot.ini file, which will cause NTLDR to display the names of the kernel (Ntoskrnl.exe) and drivers as they are loaded. This will help diagnose problems with a missing or corrupted device driver.
You can consider a simple example, and the second option: editing the BOOT.INI file from the recovery console.
The Master Boot Record is the first sector of the boot partition on the hard drive. The sector contains a partition table and a program that is tasked with loading the operating system. If the master boot record is damaged or missing, we will never boot the operating system. And sometimes this damage or absence still occurs at the most inopportune moment.
For example, one user decided to install 20 operating systems on his computer, and started creating the corresponding partitions on the hard disk (and even create them sometimes), and then, accordingly, installing. Naturally, all this once stops loading and you need to get out of the situation with dignity.
Windows XP recovery via console
We insert the Windows XP installation disk into the drive and reboot, in the BIOS we set the drive as the first boot device, if you don’t know how, read here. Next, the Windows XP installation program is loaded and after loading a menu appears, in it you need to select item number 2. To restore Windows XP using the Recovery Console, click R.
Click R and enter the Recovery Console, by the way, you can read
We have one operating system installed on the disk FROM and when asked which copy of Windows you should log in to, put a number 1 and press Enter.
If you didn't have an administrator password just press Enter if you did enter the password.
A message will appear:
That's all Windows XP recovery via console should complete successfully, type exit and reboot.
What we may not be able to do is, when you enter the FIXMBR command, an error message appears, which means that writing to the partition table (MBR) is blocked by settings in the BIOS, you need to go into the BIOS and find the Boot Virus Detection parameter (Enabled value) of this option blocks overwriting the boot sector of the hard disk, which in our case is happening.
Further, such an error may occur "Windows cannot start due to hardware disk setup errors", in this case the BOOT.INI file is to blame, to fix it, we boot into the recovery console again and enter the bootcfg /rebuild command and press the ENTER key
- Add system to boot list? .
Agree Y (yeah)
Enter download ID:
We enter Windows XP Professional.
Enter the operating system boot parameters:
Enter /fastdetect special key, the system does not detect Plug and Play devices during the boot process, you can read
Well, we have changed the BOOT.INI file and the last thing, if you have several hard drives, you can find out which letters are assigned to them with the MAP command and the devices and their corresponding letters, as well as file systems, will be displayed on the screen.