If an app isn’t working properly, you can quit it and then try to reopen it. Quitting and reopening the app may resolve the problem. (Typically, there’s no reason to quit an app; quitting it doesn’t save battery power, for example.)
To quit an app, open the App Switcher, then swipe up on the app.
To reopen the app, go to the Home Screen, then tap the app.
If quitting and reopening the app doesn’t solve your problem, try restarting iPad.