My Quicksave Disappeared

I was VERY close to the end of a large map game and I hit quicksave before a final assault on the Altarian homeworld. I reloaded to try a different tactic but then realized my quicksave was missing. In fact I had no quicksaves at all, the last one being a Campaign game quicksave from 15 days ago. For whatever reason the computer had not done an autosave in 5 hours either. I had a manual non-quicksave save file from four hours earlier and that was the most recent save. I was using quicksave before every activity in the game that can cause a crash for me so that was a few times an hour so there definitely should have been a quicksave file some place.