Weird that both quit working. Did they quit working at the same time? That could actually be software issues.
Has the device been dropped recently? Has the device gotten wet or been submerged in any liquid recently? Taken any software updates?
Until you answer those questions, try wiping app cache. Wipe system cache via recovery mode. Try a different camera app. Use an app such as
this one to see if your phone recognizes the camera hardware.