Why is my Apple ID not working on my iPhone?

Are you trying to use Face ID, and that is failing?

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

If you get through the list and Face ID still isn’t working, the iPhone may be headed for a repair. Contact Apple Support.

If this is something else “not working” and not a problem with Face ID, any error messages or diagnostics shown?

"why is my apple id not working at all: my Apple ID is not working, my phone has the latest update, it has been restarted, and camera is Clean. please advise?"

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"not working"? How so? Is it not reading your face with Face ID? You are able to log in to these forums just fine. So, the password to use for it would be no different, five it is the same Apple Account.