Why my Face ID is not working?

If your Face ID is not working, see this, If Face ID isn't working on your iPhone or iPad Pro - Apple Support and this If an alert says Face ID has been disabled on your iPhone or iPad Pro - Apple Support. If neither help, then use the Get Support link at the top of the page here to contact Apple Support for service, or make a Genius Bar appointment at your nearest Apple Store. Genius Bar Reservation and Apple Support Options - Apple