face id not work

Whoever changed your back camera most likely broke the front camera in the process.

If Face ID isn't working for you, there is most likely something wrong with your TrueDepth camera. First, look at these two articles for help. If that doesn't fix the issue, then make an appointment at the Genius Bar to have your camera issue diagnosed.

If an alert says Face ID has been disabled on your iPhone or iPad Pro - Apple Support

If Face ID isn't working on your iPhone or iPad Pro - Apple Support (AZ)

Make an appointment at the Genius Bar to have it diagnosed.

Genius Bar Reservation and Apple Support Options - Apple

habushanab Said:

"face id not work: back camera change but face id not work ?"

-------

Troubleshooting Face ID and Camera:

A. Troubleshooting Face ID:

Overview these two links:

• If an Alert Says Face ID has been Disabled on your iPhone or iPad Pro - Apple Support

• If Face ID isn't Working on your iPhone or iPad Pro - Apple Support

B. Troubleshooting Camera Replacement:

• Get Another Camera: Whoever replaced you camera placed a faulty one in there. So take it back, requesting another camera.
• Any Ungenuine Camera Message?: Did you recently get the camera replaced? If so, contact the person(s) who performed the replacement, and have them place a genuine camera in there.See Here: About Genuine iPhone Cameras - Apple Support.  They should have known better.