The simplest way to repair or re-create MBR is to run Microsoft's standard utility called FDISK with a parameter /MBR, like
A:\> FDISK.EXE /MBR
FDISK is a standard utility included in MS-DOS, Windows 95, 98, ME.
If you have Windows NT / 2000 / XP, you can boot from startup floppy disks or CD-ROM, choose repair option during setup, and run Recovery Console. When you are logged on, you can run FIXMBR command to fix MBR.
1. First, restart your computer with the Windows XP setup disk in the CD drive. If you don’t have your original disk, borrow one or download a ISO image from a torrent site.
2. When prompted, boot from the CD drive by pressing any key. If Windows loads automatically, you will first have to enter the BIOS setup and change the order of the boot devices to start with the CD drive.
change boot order
3. Once the setup loads, you will see the option to press R to repair a Windows installation.
4. Once the Recovery Console loads up, you will have to type in a number that corresponds to your Windows installation. This is normally just 1. Press Enter and then type in the Administrator password.
5. Now at the prompt, type in fixmbr. Your damaged MBR will now be replaced with a new master boot record and your computer should now be able to boot properly. Note that you may also want to run the fixboot command to repair the boot sector with a new one.