There’s not too much you can do to fix a problem when your iPad or iPhone stops working…that’s the good news. There’s just a few things you can try and these usually work. Try each of these one at a time and see if one of them will fix your problem.
1. Update your apps.
2. Force quit the app. Double-click on the home button. Find the problematic app on the bottom of your screen where it shows recently used apps. Press and hold on the app icon until it wiggles. Click on the red circle with a minus sign. Your app icon goes away.
When I’ve used this successfully: iMovie was crashing. Forced it to quit and then it worked fine.
2. Restart the device. You don’t normally need to turn off your device. However, whenever you’re having problems, it’s a good idea to do so. Press and hold the power button on the top right of the device until you see “Slide to power off” on your screen. Now, swipe to power off the device. Then press the power button to turn the device on.
When I’ve used this successfully: A strange fluttering was showing up on the screen in all apps and on the home screen. Restart and problem went away.
3. Delete the app and reinstall (use this for app-specific problems). Press and hold on the app icon on the home screen until it wiggles. Press the red circle. The app will be deleted after you confirm. This sometimes might also delete your data for that app so only try this when you have to. Then go to the iTunes store and download the app again. You will not be charged twice if you are using the correct account.
4. Restore the device. This wipes out everything and is done by hooking up the device to iTunes. I’d only use this if a bunch of apps are giving you problems as it’s a headache having to set up all your apps again.
If you have any other troubleshooting steps, please add them below.