Restore Windows 7 Master Boot Record

Source
The command we will use, bootsect.exe, is in a folder (named boot) on the DVD.

We need to know what drive letter has been assigned the DVD drive to access the folder.

Code:

Type: diskpart
and press Enter
 
Type: select disk 0 (zero)
and press Enter
 
type: list volume
and press Enter

In this screen shot, the 7 DVD is letter: G

7. Use your DVD drive letter and

Code:

Type: exit
and press Enter
 
to close Diskpart
 
Type: G: (use the letter of your DVD drive)
and press Enter
 
Type: cd boot
and press Enter
 
Type: dir
and press Enter

to verify that bootcect.exe is there (if you really need to)

8. To restore the "bootsector code":

Code:

TYPE: bootsect /nt60 SYS /mbr
and press Enter

NOTE: If this method fails to restore the MBR, you can try the bootrec command as it is also a tool for repairing the MBR.

9. When completed successfully,

Code:

Type: exit
and press Enter

This will close the command prompt window.

10. Now select Shut Down or Restart