unable to enter our admin.microsoft,com account using our email ID

Because the original global admin sign-in was protected only by the Microsoft Authenticator registration that was removed, the tenant admin account is now effectively locked out and cannot complete MFA.

When there is only one admin and that admin loses access to Microsoft Authenticator (or its original registration), self-service recovery is not possible. In this situation, Microsoft’s Data Protection team must manually verify identity and restore access.

Use these steps:

1. Contact Microsoft support by phone and have a ticket opened to the Data Protection team for a tenant lockout / MFA issue on the global admin:
   • Call the appropriate number from Customer service phone numbers.
   • When the IVR asks what the problem is, clearly state it is an Authenticator / MFA lockout for an Office 365 / Microsoft 365 for business account.
   • Confirm it is a company account, that the caller is the administrator, and that there are no other administrators in the organization.
   • Ask the agent to open a service request and route it to the Data Protection team to restore access to the locked tenant.
2. If phone support is difficult to reach, create a temporary trial tenant only to open a support ticket:
   • Sign up for a free Microsoft 365 trial tenant (any enterprise/business plan) and complete setup.
   • Go to the Microsoft 365 Admin Center for the trial tenant and open Help & support.
   • In the ticket, clearly state that:
     • There is a different, existing Microsoft 365 tenant where the global admin is locked out due to Authenticator/MFA.
     • Provide the locked tenant’s domain (for example, companyname.onmicrosoft.com and companyname.com) and the admin UPN/email.
     • Explain that the original Microsoft Authenticator registration was removed and no other MFA methods or admins exist.
   • Ask for the case to be escalated to the Data Protection team to restore access.
   • After the issue is resolved, cancel the trial subscription to avoid charges.
3. Once access is restored, sign in and immediately:
   • Re-register Microsoft Authenticator and at least one backup MFA method (phone, alternate email, or another authenticator registration).
   • Consider adding a second global admin account so that one admin can recover the other in future.

Only Microsoft support (via the Data Protection team) can unlock this scenario; community forums and self-service tools cannot modify admin MFA or restore the removed Authenticator registration.

References:

• Common problems with two-step verification for a work or school account
• Authentication methods in Microsoft Entra ID - Microsoft Authenticator app
• I cant log in to my business account because it is requiring Authenticator app which I do not have - Microsoft Q&A
• I have a Micrsoft business account and I am the admin and the only user registered under this account. I can't log in because i have replaced my phone and the authenticator doesn't work. - Microsoft Q&A
• Severity A Situation - Locked out of global admin account (MFA) - business down - Microsoft Q&A