If you or one of the users of a Windows Store app you’ve developed are having problems with the app, a good starting point may be the Apps troubleshooter that is available.
If you go to this page:
you’ll find some useful advice on what to try.
Also, down at the bottom of that page you see this with the link to launch the Apps troubleshooter:
Once launched it will guide you through:
After selecting next it checks some things and warns you that you may be required to restart:
Finally you will get to the summary screen: