Send it off to a data recovery company.
If your bios won't even see it, then changes are that software that you can get commercially won't be able to do anything either. Be prepared to spend some pretty pennies for data recovery.
If you have Best Buys near you...stop in there and the 'Geek Squad' (fucking idiots, if you ask me) will send your drive off to see if anything can be recovered.
Good luck.