Okay, well I had a scratched lens on my S4 Mini so I bought a new one for maybe £2, opened my phone up and fitted it. Not expensive and doesn't take much time (at least on my S4 mini) so if you want to see if it's the camera itself thats the problem then that's what to do. Just search "Camera Samsung J1 *your version e.g. 2016* " (make sure it's the correct year eg. 2016) and find one to order.
The other possibility is that something has gone wrong in the Android Kernel and re-flashing a version of Android (perhaps an older one) might solve the issue. I don't know if you are familiar with flashing ROMs but there are guides and it is the other likely solution.