I would guess the humidity got to it. Possibly the connections got a tiny bit of moisture and corroded. Unless you really like the thing, take out the hard drive and get a new computer. Salvage what parts might have value or use and start over. New PC's aren't that expensive to build or buy pre made. EBAY my man. EEEEEEEEEEEBAY.
Change the world. Of one person. Today.
If your equation requires either a complex combination of variables to get the desired result OR you can't seem to get the result regardless of the variables....it ain't your variables, it's your constant.