Locked out of Microsoft 365 Admin Account

hi Cefak​  If MFA has suddenly started being required for the Global Administrator account and nobody in your organization has access to the registered Authenticator method, this is unfortunately difficult to resolve through normal self-service options.

Since this is a Global Admin account, another user can't simply reset the MFA method unless you have another administrator account with sufficient permissions.

I'd recommend checking whether there is any other Global Administrator account in the tenant that can still sign in. If so, that account may be able to reset or update the authentication methods for the affected admin.

If this is the only Global Administrator account and nobody can access the configured MFA method, you'll need to work with Microsoft Support to recover administrative access to the tenant. In this situation, make it clear that this is a tenant admin lockout / Global Administrator account recovery issue rather than a normal password reset.

You may also want to check your original Microsoft 365 subscription or purchase documentation for the tenant details and have those available when contacting support, as Microsoft may need to verify ownership before restoring access.

Unfortunately, the community won't be able to bypass MFA or directly restore access to the tenant, but hopefully Microsoft Support can route the case to the appropriate account recovery team.