How to Restore Ubuntu / XP / Vista /7 / 8 Bootloader

How to fully fix the Windows bootloader using a Windows disk

XP

  • Boot on your Windows XP installation CD or XP Recovery console. You will get to a part where it asks if you want to repair or recover. To do so, press “r”. If prompted, enter your Windows XP administrator password. This will leave you at at a command line, so type in the following two commands: 
fixboot
fixmbr
  • Then type 
exit
  • Then remove your XP cd. If everything has gone well, you should come to your XP bootloader.

Windows Vista or 7 or 8

  • First boot on your Windows Vista/7/8 installation DVD.If you have one of the many OEM computers that didn’t come with a Windows installation disk, you can get the same effect with a Windows repair disk, which you can download (eg Win7-32bitWin7 64bitor create from another Windows Vista/7/8 computer (see this page for Win7 and Make your own Windows repairCD, and Windows 8 UEFI repair USB must be FAT32other Win8 guide). When you get to the Regional settings, select your Location/Keyboard setting then click next. On the next page, click on “Repair your computer.” On the next page, if it finds your Windows installation, make sure it is UNSELECTED before clicking next. Then click on “Command prompt”. From there, type in the following 2 commands: 
bootrec.exe /fixboot
bootrec.exe /fixmbr
  • Now close the two windows and click “Restart.” Take out your Windows DVD and hopefully, you will be left with your Windows bootloader. 

article from: https://help.ubuntu.com/community/RestoreUbuntu/XP/Vista/7Bootloader