My iPhone 5 can't use the Front Camera?

So I recently upgraded to iOS7 on my iPhone 5, which I got just 6 months ago.
Now I think I may have bumped my phone while it was in my pocket yesterday at work, but suddenly the camera wasn't working.
There's No Visible Damage, and I got the normal camera working, but every time I try and use the forward facing camera the app freezes. This same problem occurs on All camera apps, the front camera is not accessible… Help?

This sometimes happens to my iphone 4 sometimes its just the phone screwing up. I don't know how to fix it sorry