Only Global Admin locked out by Microsoft Authenticator MFA. How can Microsoft verify ownership and reset MFA?

I will respond in English based on your previous message. As a friendly suggestion, posting in Spanish may help your question reach a wider audience and increase the chances of receiving assistance from other community members.

Hi Jose,

Sorry to hear you're running into this issue.

Since you're the only administrator and you've been locked out of the account due to MFA, the only way to regain access is to contact Microsoft Support. They are the only team authorized to help recover access in situations involving the sole administrator account.

Please try locating the appropriate hotline for your region here: Customer service phone numbers - Microsoft Support 

Here are some tips and an example of a prompt to help you navigate the IVR more effectively: 

(When you call the support number, you may hear an introduction of about 30 seconds such as "you can visit the link...". You can ignore this introduction and wait until you are presented with the options. Then press "1" as a business email user, and again "1" for technical help.)   

• What kind of problem are you experiencing?        
• Answer: Authenticator
• What products do you use?        
• Answer: Microsoft 365 for business        
• Is this for an education or company account?        
• Answer: For companies        
• Are you an administrator?        
• Answer: Yes        
• Are there any other administrators in your organization?        
• Answer: No. I am the only admin in my tenant         
• Do you need a... Service request?         
• Answer: Yes. I need to create a ticket. Please send me directly to the Data Protection Team.     

During the phone call, you will need to provide the information associated with your subscription, such as your company name, billing details, phone number, and an alternate email address, etc. This information allows the Data Protection team to verify your identity and securely assist you in regaining access to your administrator account.     

I also recommend calling during business hours. In my experience, it can be difficult to get through to the correct support queue, and automated systems don't always work as expected. If you can't get through on your first try, I suggest trying again later or at a different time.

I hope this helps point you in the right direction. If you have any updates or additional questions, feel free to reply back and I'll do my best to assist further.