Hi Houssem LAFI
Welcome to Microsoft Q&A forum
I’m sorry to hear you are locked out of your admin account due to lost access to the Microsoft Authenticator app. Here's my suggestion:
1.Check for Other Admins: If there are other IT admins in your organization, ask them to reset your MFA settings
2.Contact Microsoft Support:
-If you’re the sole admin, please try to find the related hotline number to call the frontline let them raise a ticket for you: Customer service phone numbers - Microsoft Support
-When prompted, specify:
-In some countries, this is an automated conversation: First, when you call the hotline, they will ask you what kind of problem you are struggling with.
Answer: Authenticator.
A: What products do you use?
B: Office 365 for business.
Verification: Education or company account?
B: For companies
A: Are you an administrator?
B: Yes.
A: Are there any other administrators in your organization?
B: No.
A: I need one.... Service request?
B: Yes
3.If Your Account Is Managed by a Partner/Reseller:
-Contact your reseller’s support team to open a service request on your behalf.
4.If Support Is Unreachable:
You might consider registering for a new tenant by signing up for a trial subscription via this link Compare All Microsoft 365 Plans | Microsoft. This would allow you to create a new tenant following the provided prompts. Once set up, you can access the admin console of the new tenant and submit a support ticket requesting to speak with the Data Protection team on behalf of your previous tenant.
Please remember to cancel the trial subscription once your issue is resolved to avoid any unintended charges.
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