Plug your iPad into your computer and make sure iTunes is running.Hold down both the Sleep Button (on top of your device) and the Home Button (on the front underneath the screen).Keep them both held down from about 10 seconds. (If you see the Apple logo, you've held them too long and will need to start again.)Let go of the Sleep Button but keep holding the Home Button for about 5 seconds. (If you see the "Plus into iTunes" screen than you held it too long and will need to start again.)If the screen stays black, that's it! Your iPad should now be in DFU mode.
You can restore it with iTunes