I believe you can only restore the MBR if you used the Active@ Partition Recovery software to back it up.
You should be able to repair or re-create the MBR by using the fdisk /mbr command if the OS you are using is either Win95, 98, or ME. For NT, 2000, or XP, you can boot from startup disks or CD-ROM and select the repair option during setup and run Recovery Console. When you are logged on, from there you can then run FIXMBR command to fix MBR. Have you tried to take a look at the MBR using a disk editor like Norton Disk Editor? Since the MBR is always the first sector of the disk, check it out and see what it looks like. The first 446 bytes are the MBR. The next 64 bytes are the Partition Table. Check to see if the signature is still at the end. It should be the last two bytes in the sector. It should read 0x55AA. If the sector is unreadable, you may have to use some sort of partition/data recovery software and get what data can be recovered and save to a new location. Useful utilities: http://thestarman.dan123.com/asm/mbr/BootToolsRefs.htm For future reference: http://support.microsoft.com/?kbid=166997
