Visat will not accept my slave drive

Hello, I have a new Acer computer with Vista. I have a C and d drive the D drive is another Hard drive used as a slave drive. The system drive is the newer kind and the slave is the older kind of ribbon drive. When I bought the computer form Best Buy my old hard drive which I took out of my other computer installed on this Acer worked fine. But I was having problems with my computer. So I left the slave drive in the computer and did a factory restore for drive C. specifically The restore went great but after the The slave drive would have no drive letter assigned. It showed in Bios as a second drive and healthy. computer management it showed as a drive 0 but had no assign letter. in my computer. Even in disk management it was there under drives available. Healthy drive. All my photos and many programs are on this disk. How can I get the system to recognize it and assign it a letter so I can open it.
I took the drive out and put it in my friends computer and it also would not assign it a letter. It shows it being there too as mine did. What happened when I did the factory restore? Have I lost all the data on it. Do I have no choice but to reformat it and start again loosing so many photos? Help please!