I had an old Dell once where I corrupted the BIOS and they had a way to download a special file onto a floppy - start the computer with that floppy in the drive and it would reload the BIOS from the floppy. Don't know if your board manufacturer has something like that but you could check their web site.
Other than that, replacing the BIOS chip is about the only other way... assuming the BIOS chip is in a socket. The board manufacturer will sell you a new chip.