A cloud-based identity and access management service for securing user authentication and resource access
Hello Dejavu Mclean-Fulton,
Greetings! Thanks for raising this question in Q&A forum.
I understand this is very urgent, especially because you are the only admin and your business is blocked. The most likely reason is that this is now a full tenant lockout: when the only admin loses access to Microsoft Authenticator after changing phones, the MFA method cannot be bypassed or reset from the sign-in page or from the forum side.
- First, check once more on the sign-in page for any option like Sign in another way or another registered method. If another method exists, use that and then update your authentication methods immediately.
- If there is no other Global Admin and no backup MFA method, the next owner is Microsoft Support. You need to contact business support by phone and ask them to open a case for the locked tenant and route it to the Data Protection team for admin recovery / MFA reset. Forum moderators cannot perform this reset.
- Use the official support numbers here: https://support.microsoft.com/help/4051701/global-customer-service-phone-numbers. When the automated system asks, say business user, Microsoft 365 for business, technical support, administrator, and no other admin. That wording is commonly used to reach the correct queue faster.
- Be ready to prove ownership of the tenant, such as your domain access, billing or subscription details, and your admin account details. The support team normally uses this to validate the tenant before they can help with the reset.
- About removing the domain and moving it back: that action also requires admin access in the tenant. Microsoft’s domain removal flow needs an admin to sign in, move users and groups off the domain, and then remove it. So domain removal is not possible until access is restored first.
- If phone support does not let you reach an agent, one workaround mentioned in similar cases is to create a temporary trial tenant with a different email and use that to open a support request for the locked tenant. The expected outcome is still the same: Microsoft Support verifies ownership and helps restore admin access.
So the next action is with Microsoft Support, not from the forum side. Once you are back in, add at least one more admin account and a second MFA method to avoid this happening again.
If this answer helps you kindly accept the answer which will help others who have similar questions
Best Regards,
Jerald Felix.