My computer doesn't detect my second harddriv

Hi.

I have on my computer two harddrives, one for program files and shiz, and on the other one i usually have games and crap. When i went on my computer this morning i found that my computer only found one of the two harddrives. I rebooted a couple of times, since this have happened tto me before, and it was usually enough to just reboot, but this time it didn't work. So i decided to reformat my computer, since it really needed it anyways. After i was reformating it could not still detect it.
Any ideas?

I use Vista Ultimate 32-bit