If you have problems starting the OS and you suspect that the Windows boot loader is at fault, here you will find a way to fix this problem manually.
Restoring the Windows 7 bootloader may be required (or at least worth a try) in the following cases: when errors occur Bootmgr is missing or Non system disk or disk error; in addition, if the computer is locked, and a message asking for money appears even before Windows starts to boot, restoring the MBR (Master Boot Record) can also help. If the OS starts to boot, but it crashes, then it is not the bootloader and the solution is to look here: Windows 7 does not start.
Booting from a disk or flash drive with Windows 7 for recovery
The first thing to do is boot from the Windows 7 distribution: it can be a bootable flash drive or disk. At the same time, this does not have to be the same drive from which the OS was installed on the computer: any version of Windows 7 will do to restore the bootloader (i.E. It doesn’t matter Maximum or Home basic, for example).
After downloading and selecting a language, on the screen with the “Install” button, click the “System Restore” link. After that, depending on the distribution you are using, you may be asked to enable network capabilities (not required), reassign drive letters (as you wish), and select a language.
The next item will be the choice of Windows 7, the bootloader of which should be restored (before that there will be a short period of searching for installed operating systems).
After selection, a list of system recovery tools will appear. There is also an automatic launch recovery, but it does not always work. I will not describe the automatic recovery of the download, and there is nothing special to describe: press and wait. We will use the manual recovery of the Windows 7 bootloader using the command line. And run it.
Recovering the bootloader (MBR) of Windows 7 using bootrec
At the command prompt, enter the command:
It is this command that overwrites the Windows 7 MBR on the system partition of the hard drive. However, this is not always enough (for example, in the case of viruses in the MBR), and therefore, after this command, they usually use another one that writes the new boot sector of Windows 7 to the system partition:
After that, you can close the command line, exit the installer and boot from the system hard drive. Now everything should work. As you can see, restoring the Windows boot loader is quite simple and if you correctly determined that the problems with the computer are caused by this, the rest is a matter of several minutes.