I can't log into authenticator on my device and when I try online it asks for a code from my device!

Because the existing MFA methods (Authenticator and phone) are no longer usable, recovery depends on whether this is a work/school (Entra ID/Azure AD) account and whether there is another admin who can reset MFA for the account.

Use these steps in order:

1. Try alternative sign-in methods
   • On the MFA prompt page, choose Sign in another way (or I don't have my code / I don't have my Microsoft Authenticator app).
   • If any backup method (SMS, email, office phone, security key) is listed and still accessible, use it to sign in.
   • Once signed in, go to the Security info page and update methods:
     • Remove the old phone/app entries.
     • Add a new Phone method with the current number.
     • Re-register the Microsoft Authenticator app on the new phone.
2. If SMS or email codes are not arriving
   • Avoid repeatedly requesting codes; excessive requests can cause a temporary block where codes are not sent.
   • Check for issues described in I'm not getting my verification code. What do I do?:
     • Ensure the number is a mobile number, not VOIP.
     • Confirm the phone can receive texts from unknown numbers and that the SMS inbox is not full.
     • For email codes, check the junk folder for messages from @accountprotection.microsoft.com and mark as trusted.
   • After waiting for any temporary block to clear, try again and then update security info as above.
3. If this is a work or school account and another admin exists
   • Contact the organization’s IT help desk or a Global Admin and ask them to require re-register MFA for the user account so MFA methods can be set up again. This is the standard way to reset MFA methods when the Authenticator app/phone is lost or changed.
4. If this is a work or school account and this is the only admin account
   • If there is no other Global Admin who can reset MFA, Microsoft’s Data Protection team must verify identity and restore access.
   • Call Microsoft’s global customer service phone number for business/commercial support (see Customer service phone numbers - Microsoft Support in the referenced Q&A). When prompted by the automated system, clearly state:
     • The issue is with Authenticator.
     • The product is Office 365 for business / Microsoft 365 for business.
     • It is a company account.
     • Confirm being the only administrator and that access to MFA is lost.
   • Ask to create a service request and be routed to the Data Protection team to reset the admin’s authentication methods.
   • If the tenant was obtained via a reseller/partner and a support request cannot be opened directly, contact the partner and ask them to open a service request with Microsoft on behalf of the tenant.
5. If Microsoft support cannot be reached from the locked tenant
   • As a workaround, create a temporary trial tenant (for example, a Microsoft 365 Business/Enterprise trial) and sign in as its admin.
   • From the new tenant’s Microsoft 365 Admin Center → Support → Help & support, open a ticket explaining:
     • There is a different, existing tenant where the admin is locked out due to MFA.
     • Provide the locked tenant’s domain and admin UPN, the error messages, and confirm being the sole admin.
   • Work with support/Data Protection to verify identity and reset MFA on the original tenant.

Once access is restored by any of the paths above, immediately:

• Add multiple MFA methods (Authenticator on the new phone, SMS to the current number, and at least one backup method such as email or security key).
• Verify that the phone number and email shown on the Security info page are correct and recognizable.

References:

• Use a screen reader to set up and troubleshoot multifactor authentication
• Common problems with two-step verification for a work or school account
• 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
• I need to reset my mfa methods - Microsoft Q&A
• Cannot authenticate with E-mail when logging into Microsoft Authenticator(iOS). - Microsoft Q&A
• Having problems getting text codes to confirm my account - Microsoft Q&A
• Requesting a Tenant Admin MFA Reset - Microsoft Q&A