PS2 isn't reading why?

I've owned a PS2 slim since it first came out. It worked fine and dandy and then suddenly stopped reading discs. Plus it wouldn't ever read God Of War or God of War II. I was wondering why exactly. It ran perfectly smooth until I attempted to play God Of War. It wouldn't read the game at all so I got annoyed and attempted to switch to another game. It wouldn't read that game either now. It won't read any games at all. Not even PS1 games now. I was wondering what's wrong with it and if I can fix it or I should just get a new one. Any advice would help because I really really really want to play my God Of Wars.