If an app you installed unexpectedly quits, stops responding, or won’t open, first try to restart the app. Note: To restart an app, double-press the Home button then swipe up on the Desired app to close it.
Restart your device, press and hold the Sleep/Wake button until the red slider appears, then Drag the slider to turn your device off. Note: If iPhone is not responding, as a last resort perform a force restart. To force restart your device, press and hold both the Home and Sleep/Wake buttons for at least 10 seconds, until you see the Apple logo. If your iPhone still does not respond, get help.
To turn back on, press and hold the Sleep/Wake button until you see the Apple logo.
Check for iOS updates, plug your device in to power and connect to the Internet with Wi-Fi, then select Settings > General > Software Update. If an update is available select Download and Install, then follow the on screen prompts. Note:Learn more from Apple support article: Update the iOS software on your iPhone.
Check for app updates, open App Store and select Updates. If updates are available, select Update All. Note:You might need a Wi-Fi connection to update some apps.
Try installing a different app that you don't have on your device from the App Store. Note:Remember to use the same Apple ID that you used to download the app that you're having issues with.
Delete and reinstall the app. To delete the app, select and hold the app until it jiggles, then select the X icon on the app.
To reinstall the app, press the Home button, go to the App Store and download the app again. Wait for the app to download, then open it from the Home screen. Note:Learn more from Apple support article: Download past purchased from iTunes.
If you see this issue again, Contact the app developer for help. Find the app in the App Store, select the app, then select Reviews.
Underneath App Store Customer Reviews, select App Support.
To manage App data, from the Settings screen, select General.
Select Storage & iCloud Usage.
Select Manage Storage.
Select Desired App. Note: For this demonstration, Music was chosen.
Select Edit then make desired changes to App Data.