Why is My rear camera and flash is not working?

Hello,

Your flash isn't working

Use Control Center to test the LED flash. Turn the flashlight off and on. If the LED flash doesn't work as a flashlight, contact Apple Support.

If the flash isn’t working, or it goes off every time you take a photo, check your flash settings. Tap in the upper left of the screen to choose a different setting.

If you take extended video with the flash on, or you’re using the device in a very warm environment, you might see a message that says the flash is disabled. The message remains until your device cools down.

If you still need help

If you still can't take a photo, your photos don't look right, or you need help with something else, contact Apple Support.

From:

Get help with the camera on your iPhone, iPad, or iPod touch - Apple Support

This may be a hardware problem. I would suggest contacting Apple Support as they can look more into this and guide you in the right direction.