When an app (or several) are misbehaving, I usually go through the following steps:
1. Force Close - open the multi-tasking bar (double tap the 'home buttom' or use multi-gesturing and swipe up):
a. iOS 6.x - press & hold an app until all begin to 'jiggle'; find the offending app(s) and press the 'red circle w/ minus sign' - return to the home screen & try again.
b. iOS 7.x - find the offending app - then press and drag to the top of the screen - return to the home screen & try again.
2. Restart - press & hold the 'Sleep/Awake' (a.k.a. power) button until a red slider appears (may take a few seconds) - move the slider to turn off the iPad; then press & hold the same button until the Apple logo appears - wait for a restart.
3. Reset - press & hold the 'Power' and 'Home' buttons simultaneously until the Apple logo appears - this may take a longer time, so have patience; the iPad will 're-boot' - NOTE that none of these maneuvers will alter your apps, files, or settings.