You can restore Windows Boot Loader manually using Windows utilities

Introduction

Should you need to restore Windows Boot Loader, proceed as described in this article.

One of the symptoms when you need to do this, is when you have the BOOTMGR is missing error on an attempt to start Windows.

Solution

Windows 2000/XP/Server 2003 Installation CD

Boot the computer from the installation CD, start Recovery Console and run fixmbr and fixboot commands.

Further information is available at:

• Windows 2000: http://support.microsoft.com/kb/229716/
• Windows XP: see here
• Windows Server 2003: http://support.microsoft.com/kb/326215/

(!) If the system partition was not restored to its original position, then the boot.ini file needs to be updated.

This can be done with the Recovery Console command bootcfg /rebuild

Further information is available at:

• Windows Server 2003: http://support.microsoft.com/kb/317521/
• For Windows 2000:
  
  • Create a boot disk first: http://support.microsoft.com/kb/301680/
  • Then change the boot.ini from Windows: http://support.microsoft.com/kb/311578/

Windows Vista or Windows 7 installation CD/DVD

Boot from Windows Vista installation disc, select language and keyboard or input method, click Next and choose to Repair your computer. Then you will need to select the operating system that you want to repair. In the System Recovery Options dialog box click Command Prompt and type the following:

Bootrec.exe /FixMbr
Bootrec.exe /FixBoot

If you want to completely rebuild Windows Vista Boot Configuration Data, then you should issue the following command:

Bootrec.exe /RebuildBcd

This command scans all disks for installations that are compatible with Windows Vista. Additionally, this option also allows select the installations that you want to add to the Boot Configuration Data store.

Further information is available at https://support.microsoft.com/en-us/help/927392/use-bootrec-exe-in-the-windows-re-to-troubleshoot-startup-issues

 Windows 8/8.1

See instructions at Microsoft Knowledge Base http://support.microsoft.com/kb/2622803/

Windows 10

Repair MBR in Windows 10: click to expand

1. Boot from Windows 10 installation DVD.

2. Press any key at the “Press any key to boot” message

3. When you get to the screen with "Install now" button, сlick the Repair your computer button in the lower-left corner.

4. Click on Troubleshoot

5. Click on Advanced options, then select Command prompt

6. Use Bootrec tool to repair the MBR by running the following commands in command prompt, one after the other:

• bootrec /RebuildBcd
• bootrec /fixMbr
• bootrec /fixboot

7. Exit and reboot the computer

 

You can find more information at https://neosmart.net/wiki/bootrec/#Bootrec_in_Windows10

More information

Please keep in mind that fixmbr is supported only on x86-based machines.