Face id and front camera not working

Your phone uses several components that make up the the Face ID system. Unfortunately for those of us who want to do our own repairs, Apple has paired those parts with the motherboard, meaning you cannot replace the part yourself and have Face ID continue to work. The front camera assembly is one of those parts, so if it has failed, then only Apple can repair it in order to restore your Face ID.

That being said, there are three separate components that are part of the front camera assembly; the front camera, the dot projector and the infrared camera. Although they only come as a single part, as it turns out the front camera by itself is not paired to the logic board, so with a little cutting and hacking, it is replaceable on its own. I helped out on an iPhone 11 Pro guide showing how to do that, but the exact same procedure will work for an iPhone X if it's just the front camera that's affected.

iPhone 11 Pro Front Camera Replacement Without Losing Face ID - iFixit Repair Guide

My daughter-in-law had an iPhone X with a similar problem and I bought the parts needed to replace just the front camera, but once I got into investigating the issue it turned out that it was the IR camera that was the problem rather than the front camera. I haven't figured out how to resolve the issue yet, but did go ahead and replace the whole front camera assembly. As expected, Face ID does not function, but the camera at least works again.