How can I use my Face ID when it disable
just turn off itself
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 fixa 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