How do I fix Lumia Camera?

[N_Studios]

Lumia Camera has been acting up on my Lumia 635 for a few months now. I can't get the app to launch, it won't update or install, and in the Store, it says the app is installed, even though the app doesn't show up in Storage Sense or the All Apps list. How do I fix the app?
I have a Lumia 635 running Windows Phone 8.10.14219.341 and Lumia Cyan.

 

[Roland Schlangen]

backup your Phone and do a hard reset