Not Recognizing the Hard Drive

I had a user who disassembled a workstation and was swapping out hard drives. The system will now no longer recognize the original hard drive for the system and I have tried changing hard drives and have the same results. I am thinking that the BIOSmay be corrupt, when the hard drive is connected it will either lock the system up or go unrecognized. Could there be any other items I am missing? I am trying to find a BIOS but the system is a custom build with one motherboard manufacturer and another manufacturers BIOS. Any ideas?