The iPhone 3G is essentially a small computer and just like on larger computers, sometimes programs freeze and keep you from using the phone for anything else. In this situation, it’s easy to quit that program.
Simply hold down the Home button at the bottom center of the phone for at least six seconds. This should quit the program and return you to the Home screen.
Once that’s done, restart the phone and you’ll be all set.
If that doesn’t work, though, try resetting the iPhone 3G.
