If you own a 2nd or 3rd generation Apple TV and you've been experiencing problems with it or it just doesn't seem to do anything at all, you can restore it in iTunes in pretty much the same way you can any other iPhone, iPad, or iPod. Recently, Apple pulled the Apple TV 6.0 software update after reports of it bricking user's Apple TV's started trickling in. If that's something you went through, the only way to get it back in working order is to restore it using iTunes.
That's all there is to it. Go ahead and set up your Apple TV with your television again and make sure it's functioning properly again.
If you're still having problems after a restore to factory settings, our iMore forums are a great place to ask questions and get lots of help from other users. Be sure you check them out or drop a comment below.