If something isn’t working right, try restarting the problem app or iPad.
Restart an app. If an app isn’t working properly, you can force it to quit, then try to reopen it. (Typically, there is no reason to quit an app; quitting it doesn’t save battery power, for example.) To quit the app, double-click the Home button, then swipe up on the app in the app switcher. Opening it again may resolve the problem.
Restart iPad. Press and hold the Sleep/Wake button until the slider appears. Drag the slider to turn off iPad. To turn iPad back on, press and hold the Sleep/Wake button until the Apple logo appears.
Force restart iPad. If iPad isn’t responding, press and hold the Sleep/Wake button and the Home button at the same time for at least ten seconds, until the Apple logo appears.
If iPad still doesn’t respond or turn on, see the Apple Support article If your iPad won’t turn on.