If it is at all possible, post the BIOS ID string number. It is the number that appears at the bottom of the very first boot screen when you first turn your system on. It will look like one of these two examples:
Award/Phoenix BIOS: 2A59CG0HC-00 or i430TX-SMC67X-ATC-5030C-00
AMI BIOS: 51-0102-1101-00111111-101094-AMIS123-P
You will need to hit the "Pause/Break" button on the keyboard the moment you see this screen so that you can write the number down. If it is too fast for you, then download the BIOS Wizard and it will be able to give you the ID.
If the motherboard is not working, then please list all facts about the board and any numbers/letters found on the board. Example: "It has 4 PCI slots and 2 ISA slots. It has 4 EDO memory slots and it's a socket 7 board with SiS 530 written on one of the chips." This will help us to help you ID the board as fast as possible. If it is a laptop you will more than likely need to go to the laptop manufacturer for the bios as generic bioses usually will brick your laptop.