My Face ID is disabled how can I active it back ?

What was the result when you followed the guidance in the Related Article above your name on this page, that you were reading just before you posted here? If the Related Article doesn't answer your question please post back with more details about the issue and another user in this user-to-user forum will try to help.

Well, the link says the next step is to contact Apple Support, and there is a link in the article to do that.