That missing pin should be missing if it is a newer powersupply. That pin was used for the -5 Volt wire that was a left over from the AT days and it was removed from the ATX standard quite some time ago.
Your explanation is a bit vague, does your computer not work at all? Or does the restart button in windows not work?
Can you tell us a bit more about your system as well as anything off that might have happened recently?
Finally got it working after re-re-seating EVERYTHING. Thanks for your help guys.