What do you mean by frozen? What iOS are you running? Which iPad do you have? Have you closed GarageBand from the background apps and restarted? If that doesn't work, try re-'booting' your iPad by holding the sleep wake button on top and the home button (for about 10-15 seconds) until it shuts down and you see the apple.
In iOS 5 it looks like this, it is different in iOS 7