Lost access to authenticator app

Dear @Sally Barnard

I understand that you have lost access to the Microsoft Authenticator app that was registered to your administrator account. When you select “Sign in another way,” Microsoft still only offers Authenticator verification, so you currently have no usable MFA method and cannot access your Microsoft 365 account.

If you are not the only Global Administrator in the tenant, the quickest solution is to ask another Global Administrator to reset your MFA registration:

1. Sign in to the Microsoft Entra admin center.
2. Go to Identity > Users > All users and select the affected administrator account.
3. Select Authentication methods.
4. Select Require re-register multifactor authentication.
5. If necessary, revoke the user’s MFA sessions as well.

After this, sign in again and register Microsoft Authenticator on your new device. This is the recommended approach when another administrator is available.

If you are the only Global Administrator and have no other working verification method, you cannot reset your own MFA registration because you cannot access the admin center. In this case, the tenant is effectively in an administrator lockout state, and you will need to contact Microsoft Support and request assistance with tenant/admin account recovery through the Data Protection team. Microsoft Q&A cannot reset MFA or make changes to your tenant.

I also recommend setting up at least two administrator accounts and multiple authentication methods once access is restored, so a lost device does not lock the organization out again.

For the official guidance, please see Manage authentication methods for Microsoft Entra multifactor authentication.

I hope this helps you regain access.