My Face ID isn’t working. What do I do?

Hello,

Apple has several documents helping you with Face ID.

This document is specific to seeing a 'disabled' Face ID alert, and explains what to do when you see that notice. --> If an alert says Face ID has been disabled on your iPhone or iPad Pro - Apple Support

If you don't see a 'disabled' message but do have general issues with Face ID not working properly, explore the list of things to try in this document: If Face ID isn't working on your iPhone or iPad Pro - Apple Support

If the first 8 don't solve the issue then use #9, contact Apple.

The link above your post should help. I’ve copied the steps below. Step 3 is very important.

1. Update your iPhone or iPad to the latest version of iOS or iPadOS.
2. Check if there is an issue with Face ID in your iPhone's parts and service history. To do this, open the Settings app, tap General, then tap About.
3. If you still can't enroll your face or unlock your device with Face ID, you can take your device to an Apple Store or Apple Authorized Service Provider, or contact Apple Support about your iPhone or your iPad.

Only a trained technician should service your device. Improper repair, modification, or use of nongenuine Apple components in the laser systems might prevent the safety mechanisms from functioning properly and could cause hazardous exposure and injury to eyes or skin.