Hello,
Try the following steps on another computer and login to your Microsoft account:
- Please log into the security info page: https://account.microsoft.com/security
- Please select advanced security options > under the "Text a code" tab click the remove button to remove the existing phone number.
- Then re-adding a new email address by clicking the "Add a new way to sign in or verify" link then select the "email a code" option > enter a new email address.