Locked out after losing Authenticator – only Global Admin

Hi Community,

I’m the only Global Admin for my Microsoft 365 tenant. I recently changed my domain UPNs and reconfigured accounts, but I lost access to the Microsoft Authenticator app that was registered for my admin account.

I requested to sign out of all sessions, and now I’m completely locked out — I cannot approve MFA prompts since the Authenticator app is gone. I don’t have any backup MFA methods configured (phone/SMS), and there is no second Global Admin account in my tenant.

When I try to log in, I only get the MFA request which I cannot complete.

Question:

What is the recommended way to regain access to my tenant in this situation? I understand Microsoft may require domain ownership verification (TXT record in DNS), but I’d appreciate step-by-step guidance or a direct way to reach support for account recovery.

Thanks in advance for your help!