Phone number

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.   *

If you can get a code and sign in, you need to change/add the number on your Apple ID. Look in the Security section when signed in online. 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

mortego52 Said:

"Phone number: Can not update my App Store because the phone number is not on use any more"

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To Get the Phone Number Changed,,,

Contact Apple Support:

Ask the Apple Rep to modify it over the phone. If permitted to do so, then inform to modify the Phone Number associated to your Apple Account, to what it should be. Important: Perform a Trial & Error login session with the Apple Rep prior to ending the phone call.

Contact ApleSupport. 

• Contact Us - Choose Locations
• Proceed from there as Necessary
• Why the Wait: Phone calls are taking a bit to go through at the moment, due to lots of calls. With the Coronavirus Pandemic, many are at home at the moment, with much time on their hands to contact Apple. So, just stay on the line, and you will get through :)