Face ID on my iPhone 12 has stopped working

Hello

The Face ID function on my iphone 12 has stopped working. Therefore I need to now use the passcode to unlock the phone, which is annoying.

When I go to 'Face ID and Passcode' the functionality at the top where it says 'Use Face ID for' is greyed out; similarly 'Set up Face ID' is also greyed out. The functionality on this menu below that is active though.

IoS is up to date and I've turned the phone on and off. I also found another piece of advice online which said turn on airplane mode, wait for 30 secs, turn off, wait 30 secs, turn on...but that didnt work either. There's no obvious damage to the camera.

I'd welcome any ideas to solve this!

Adam

[Re-Titled by Moderator]