I would recommend using sections 1, 3, and 5 of the iPad Troubleshooting Assistant found here http://www.apple.com/support/ipad/assistant/ipad/#section_1. If you get to step 3, I suggest closing all the apps. Here is step 1 to get you started:
To restart iPad, first turn iPad off by pressing and holding the Sleep/Wake button until a red slider appears. Slide your finger across the slider and iPad will turn off after a few moments.
Next, turn iPad on by pressing and holding the Sleep/Wake button until the Apple logo appears.
Is iPad not responding? To reset iPad, press and hold the Sleep/Wake button and the Home button at the same time for at least 10 seconds, until the Apple logo appears.
If your device does not turn on or displays a red battery icon, try recharging next.