Authentication app

If you've purchased a new phone and your Microsoft Authenticator app is not linked, you may find yourself locked out of your account due to two-factor authentication (2FA) requirements. Here are some steps you can take to regain access:

1. Alternative Sign-In Methods: Check if you have any alternative sign-in methods set up, such as SMS or email verification. If available, try using those to log in.
2. Contact Support: Since you may be unable to access your account, contacting Microsoft support is essential. If you are the only administrator for your Microsoft account, you will need to involve the Microsoft Data Protection team. You can do this by calling the support hotline and following the prompts to raise a ticket for assistance.
3. Create a Trial Tenant: As a workaround, you can create a trial Microsoft 365 tenant. This will allow you to access the Admin Center and submit a support ticket directly from there. Make sure to cancel the trial subscription once your issue is resolved to avoid any charges.
4. Reset MFA Settings: If you have access to another admin account in your organization, ask them to reset your multi-factor authentication (MFA) settings. This can be done through the Microsoft Entra Admin Center.

These steps should help you regain access to your account. If you need further assistance, please feel free to ask.

References:

• I cant log in to my business account because it is requiring Authenticator app which I do not have - Microsoft Q&A
• Microsoft authenticator sending me into a spiral - 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