It often happens to me that a lot of Windows 8 Metro apps need to be repaired (i.e. cannot be opened). Is there a way to repair them all at once?
If they don't work, test the app troubleshooter.
Is the tool able to fix the issues?
I think I got the patch:
The only thing you need to do is to go to Control Panel, and in the search bar, type "guest" then you got "create guest session". Click on it, validate then go the Start screen and click on your avatar in upper right, and click "Guest"
It will load it, it take one or two minutes, then return to your session by the Start screen and all metro apps will work again.
I think this reactivate some DLLs or components, but it works 100%.