Does this happen in one app only? If so, force close the app, then see if that helped. To force close, double tap the Home button to switch to the App Switcher, then tap the thumbnail of the app that misbehaves and slide it to the top of the screen.
If you experience this problem in more than one app, restart your iPad. Turn it off and on again.
Force starting might help as well: press and hold Home and Power button until you see the Apple logo. As soon as it’s visible, let go of both buttons. The iPad will power up on it‘s own.
Resetting all settings might help, if everything else mentioned above won‘t solve the issue. Open Settings (the app), go to General - Reset - Reset all Settings. This will set back everything to default. You‘ll have to set up your networks, ... again afterwards.
Your last option would be to erase the iPad and set it up as new.
Hope that helps.