All I can suggest it trying to recognize it in the BIOS. Do you know how to get into the BIOS when your machine boots up? On mine you press Del. Sometimes it's F1 or F9 I think.
Anyway, once in you can see if it will detect your drive. I'm a bit vague about what's in there, but you can look at your drives and your boot sequence and see if it lists your drive.
Did you check the cabling, nothing loose?