Hi @Kriti Kumar,
Thank you for reaching out to Microsoft Q&A Community.
As per the description you have shared, we understand that you can't be able to sign into your admin account due to Authenticator issue.
May I ask if your organization has another global administrator who still has access to the Microsoft 365 admin center?
Scenario 1 - If there is another admin available, they can help reset your MFA by following these steps:
Sign in to the Microsoft Entra admin center.
Locate your user account and go to Authentication methods

Select “Revoke multifactor authentication session”

Then choose "Require re-register multifactor authentication".

Once this is done, you’ll be prompted to set up MFA again on your new device during your next sign-in.
Scenario 2 - If you are the only administrator in your organization, you can contact Microsoft Support directly via phone to open a support case. This will allow you to speak with a representative who can assist with verifying your identity and initiating the recovery process: Customer service phone numbers - Microsoft Support

In some regions, the initial interaction may be automated, so here’s a general idea of how the conversation might go to help you prepare:
What kind of problem are you experiencing?
Answer: Authenticator
What products do you use?
Answer: Office 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 direct to the Data Protection Teams.
If your organization's Office 365 Business subscription is from a partner or reseller, and the global administrator is unable to open a service request on your end, contact the reseller's support provider to help open a service request on behalf of you instead.
Scenario 3 - If you still cannot reach to agent, I recommend that you follow these steps:
- Set up a Temporary Microsoft 365 tenant using trial license: Microsoft 365 Business Plans and Pricing


- Raise support ticket
Once you have created and registered a free trial, please visit Microsoft 365 Admin Center and click " Help & Support " to raise your ticket.

Please remember to cancel the trial subscription once your issue is resolved to avoid any unintended charges.
I hope the above information is helpful for you. If there's anything else I can help you with, please feel free to reach out again.
Looking forward to your response.
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