Well, I've used Audacity before, mainly importing songs and editing them and cutting bits out etc, and now when I use it, i select open file and choose a song from my desktop, and then when audacity plays it, it plays it really quickly in about half a second and it sounds poo, has anyone else had this problem and if so would you know how to fix it?

I'd appreciate the help a lot
I've had similar problems, and I've found that with any problems, you should just re-install audacity. You won't lose audacity files on your cpu, it's risk free.