Hello @Martha Skjellerup
Thank you for reaching out to Microsoft Q&A.
In this situation you have 2 ways to solve this issue.
1.If you have another Global admin of your tenant
2.If you are the only Global admin of your tenant
If you have another Global admin of your tenant, you can ask them to make change in Entra ID for your account so that you can re-register for MFA in authenticator app.
To perform this, you can ask another Global admin to follow below steps,
1.Admin has to login to Azure portal and access Azure active directory.
2.Once done they have to go to users' blade on the left.
3.Click on the user account which has been locked out.
4.Click on Authentication methods and click on “Require re-register multifactor authentication”.
Now when you try to login to Azure services it will prompt you to register for MFA again.
If you are the only global admin on the account and are blocked entirely, you can reach out to our support team. You can look into below article to get support numbers depending on your country.
or creating a ticket through a different account: https://learn.microsoft.com/en-us/microsoft-365/admin/get-help-support?view=o365-worldwide#phone-support
While creating a ticket with Microsoft support team. Give them the tenant ID which is locked out in your description. Tell them that no admin account has access anymore and your partners also have no access anymore.
Once you create a ticket with support team you will have to work with our data protection team. You will have to first prove your identity against your tenant for security purpose. Post that this team will help you with help you in getting access to your tenant or unlock your account depending on your scenario.
Also, for the future, you can create an emergency access account (break glass) in Azure AD. This account will help prevent being accidentally locked out of your Azure Active Directory (Azure AD) organization because you can't sign in for any reason.
https://docs.microsoft.com/en-us/azure/active-directory/roles/security-emergency-access
I hope this clarifies things. Please contact us if you have any additional questions.
If this answers your query, do click Accept Answer and Yes for "Was this answer helpful". And, if you have any further query do let us know.
Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.
Best regards,
Sakshi Devkante