1.Please check if you haven't disabled the camera app from phone main settings.2. Download a launcher and see if the camera app appears.3. If the problem still remains, i suggest you should factory data reset your phone and use the camera app.In case...
Thats a very vauge question1. If you are using the camera app for longer period of time, the phone is bound to heat up.2. Intense gaming sessions on the phone3. Third party eiditing apps or anything that throttles the processor
