Your iPad may have a hardware fault. You should first attempt a forced-restart of your iPad:
- On an iPad with a Home button: Press and hold the top button and the Home button at the same time. When the Apple logo appears, release both buttons.
- On other iPad models: Press and quickly release the volume up button, press and quickly release the volume down button, then press and hold the top button. When the Apple logo appears, release the button.
If no improvement is observed, you will would be well advised to seek assistance from the technicians at the Genius Bar of your local Apple Store - where you iPad can be tested and assessed:
Genius Bar Reservation and Apple Support Options - Apple