Microsoft 365 features that help users manage their subscriptions, account settings, and billing information.
May I ask are you a normal user or the IT admin of your company? If you are a normal user, ask your IT admin to reset your MFA by using this article: Manage authentication methods for Microsoft Entra multifactor authentication - Microsoft Entra ID |…
If you are the IT admin and there is no other admin left that can reset your MFA, please contact Microsoft data protection team.
Please visit the following page and reach out to phone number via: Customer service phone numbers - Microsoft Support
From what I know, you will need to get past the initial AI system to reach the live support team. You can refer to the guide below for tips on how to get through more easily:
If you have tried phone support and it's not working, please follow this link to create a trial tenant: https://www.microsoft.com/en-us/microsoft-365/business/microsoft-365-business-basic?msockid=3eb6980b5c6860e63a588d0c5d1761d6 - after that you will be able to access to Microsoft 365 Admin Center to raise the ticket
Assuming that you have already created an account after registering a free trial and you can go to Microsoft 365 admin center and click "Help & support" icon to raise your ticket.
Please mention that you are raising ticket on behalf of the affected tenant that you do not have access to.
On the other hand, if you do create the trial and it resolves the issue, please remember to cancel the subscription afterward to avoid any related charges.
I hope my information is helpful. Please give me any updates once you get this resolved.