How to Repair the MBR on Windows 7
Sometimes you can corrupt the Windows MBR (Master Boot Record) unintentionally, through the installation of another operating system. You'll need to repair it before Windows can reboot. The error message that you usually receive is "Operating system not found." To repair the error, you'll need a utility such as MbrFix.exe and run it from a floppy, optical or USB drive and follow the instructions from the installation DVD to repair your MBR. While these directions are specific to Windows 7, you may be able to use the knowledge gained to apply to your particular Windows installation.
Things You'll Need
- Windows 7 installation disc
Insert the Windows 7 installation DVD and boot from your DVD drive. You may have to change the boot order through system BIOS to boot from your DVD.
Choose your default "Language," "Time" and "Keyboard Input" on the first window and click "Next."
Click on the "Repair Your Computer" option to gain access to the System Recovery window. Now choose "Command Prompt" to run the Bootsect.exe utility. Bootsect is located inside the boot folder so change your directory to boot. Now run "bootsect /nt60 C:\" (without quotes) if you had Windows 7 initially installed in the C partition. Alternatively, you can run "bootsect /nt60 SYS" or "bootsect /nt60 ALL" (without quotes) to repair the system partition or all partitions. Eject the DVD and restart your computer. Your computer should now boot Windows 7 again.