Reinstall the OneDrive app from the App Store. You can let go of both buttons after the Apple logo appears. Perform a “soft reset” by pressing and holding both the Sleep/Wake and Home buttons simultaneously for at least 10 seconds until you see the Apple logo. Tap the 'X' in the corner and then accept the confirmation message to delete it. Uninstall the OneDrive app by pressing and holding the OneDrive app icon.
The best way to reset the app it to uninstall and reinstall it.
