Wow, that sucks. I have an old computer, but it's still pretty good. Maybe you could get a new one? I'm pretty sure they only cost like $70. I'm saving up for a new one. *nods*
When a computer gets like that, the only thing you can really do is a system reboot.
That means wiping everything from it and restoring its settings to how it was when you first got it. If you back everything up online, you shouldn't lose anything.