It doesn't happen often, but the first thing to try is to quit the app. Your can do this by hitting the home button twice to bring up your multi-task bar. It will show all the apps that you have visited. By long pressing the app in question until it jiggles. When you see the red circle with the negative sign press that. It will only quit the app and not delete. Than try to re-open the app and test out. If that doesn't work, restart the iPad by pressing the power switch down to power off. Third is to do a reset by holding the power switch and home button together until you see the apple logo. Hope that helps!