Hello Default_20251617,
Hope you are doing well. Thank you for reaching out to the Microsoft Community. We are happy to assist you.
I'm sorry to hear that you're having trouble accessing your Microsoft work account due to the issue with your phone and Multifactor authenticator.
Normally, if you changed your phone, you are required to reset authentication method. But may I know have you set up any different authentication method, such as a verification code sent to your alternate email. If so, can try with select "Use a different verification option" on the sign-in page and follow the prompts.
If you still can't access your account, you'll need to reset authentication method for your account. Please note that as a community moderator, I have limited permissions and resetting the authentication method may require special permissions that are ONLY available to administrator. We recommend that you contact global administrators and ask them to reset the authentication method. Admin can do it by follow Manage user authentication options. (If you are not sure who is your admin, can refer this How do I find my Microsoft 365 admin? - Microsoft Support).
- Sign in to the Microsoft Entra admin center as at least an Authentication Administrator.
- Browse to Identity > Users > All users.
- Choose the user you wish to perform an action on and select Authentication methods. At the top of the window, then choose one of the following options for the user:
- Require re-register MFA deactivates the user's hardware OATH tokens and deletes the following authentication methods from this user: phone numbers, Microsoft Authenticator apps and software OATH tokens. If needed, the user is requested to set up a new MFA authentication method the next time they sign in.
- Revoke MFA sessions clears the user's remembered MFA sessions and requires them to perform MFA the next time it's required by the policy on the device.

If you are the only administrator and cannot access your account, it is suggested to contact the Data Protection team as we are from the community team and are not authorized to reset any user/administrator accounts. The Data Protection Team is the only support team to verify and reset the account.
Please find support phone number for your country here: Find Microsoft 365 for business support phone numbers by country or region - Microsoft 365 admin | Microsoft Learn
Here are some tips and an example of a prompt to help you navigate the IVR more effectively:
In some countries, it is an automated conversation like: First, when you call the hotline, it will be asked as follows:
IVR: What kind of problem are you concerned about?
She: Authenticator.
IVR: What kind of product do you use?
You: Office 365 for business.
IVR confirmation: education or company account?
She: For companies
IVR: Are you an administrator?
You: Yes.
IVR: Do you have the other administrator in your organization?
You: No.
IVR: Do you need a... Service request?
She: Yes
->You can also refer to customer service phone numbers- Microsoft Support
You can also try the following conversation:
- Dial the phone number.
- IVR: "Welcome to Microsoft Support. Are you calling home or for business?"
- IVR: "How can I help you today?"
- You: "Support for data protection"
- IVR: "Do you already have a case number?"
- IVR: "Do you have an Access ID?"
- IVR: "Please hold while I transfer your call to the appropriate team."
Thank you for your precious time and your kind understanding.
Sincerely,
Nafis Iqbal Shuvo