My Iphone doesn't recognize my camera

My Iphone does not seem to recognize the rear camera as I cannot use it on any app. When I open the stock camera app it just shows a black screen when I am trying to use the rear camera, however when I flip it and use the front (selfie) camera everything is fine. On other apps, like snapchat for example. I can't even switch to the rear camera, the app does not think that the camera exists. I can't access my flashlight either. Very similar problem, even when my phone shows that the flashlight should be at the maximum setting nothing actually happens.