Pulled it out for what? Obviously you did something that messed it up. Did you drop it or bang it? (could have caused hard drive problems). Did you clean inside it? What did you use to clean it? Have you ensured all internal and external connections (power, data, etc) are snug?
To me this sounds like probably a storage problem more than anything else. That is a pretty old computer you have there and your ooooooooooooold hard drive might have taken a bang and already been on it's last legs and you knocked those legs out from under it.
Do you have a secondary machine you could plug the hard drive into to run diagnostics and/or to pull data off of it before it totally croaks on you?