Chosen Solution

I am a cellphone repair technician, and I just did a 12 pro max back glass replacement and now the front camera isn’t working. My question is what cause this to happen.

Check if anything is blocking the camera sight. If any accessory is hindering, remove it and check the camera again. Toggle between the front and back camera to check if issue is with both or a single camera. If your device hangs during the toggle, force close the camera app, restart the device and try again Regards, Will