If your iPad's screen goes black after about five minutes of inactivity and no amount of screen tapping gets it back, it's probably not broken—just sleeping to save power so that the battery lasts longer.
Some users find this annoying, but it's easy to change. You can adjust the length of time the screen stays on before the system goes to sleep.
- Go to Settings > General > Auto-Lock
- Adjust how long you want the screen to stay on before it goes blank.