Change trusted number

You need to change/add the number on your Apple ID. You may have to add the new number before you can remove the old number. After the change, allow up to 24 hours for the change to sync. Before trying to make the change, sign out of Messages/FaceTime on all devices/computers.

Apple ID - Manage    

See if anything here helps.  If necessary, you can use account recovery as explained in the link at bottom of the article.

Verification code - how to get one and sign in with two-factor authentication.   

See if anything here helps. Link to contact Apple Support at the end of the article.

How to use account recovery when you can’t reset your Apple ID password - Apple Support

You are welcome. You still should be able to log into your Apple ID and change the number associated with your Apple ID.

Did you try contacting Apple Support using the link in the article above?