Camera App disappeared

My camera app on my Android phone has disappeared. - It all started yesterday. Everything had been working fine until then, but all of the sudden, my camera app didn't respond anymore (*Can't connect to camera* was the message I was getting). I got the same message when starting apps that used the camera (e.g. Snapchat). I went to *Settings->Apps*, and forced-quit every single app and stopped every process; still, nothing. At that point, I decided to hard reset my phone, and now, there is no camera app at all. I have tried looking for it in the disabled apps directory in *Settings->Apps*, and still, it is nowhere to find... I am really frustrated, as I can't use my camera at this point in my mobile phone (neither rear- nor front-camera)... Is there anything I could do to solve this issue? **SPECS**: - Phone: BQ Aquaris E4.5 - Android: Version 5.0