SHe is the only one that has global admin rights
Thank you for letting me know.
If she is the only Global Admin, then the only way forward is to contact Microsoft 365 Business support directly via phone https://support.microsoft.com/topic/customer-service-phone-numbers-c0389ade-5640-e588-8b0e-28de8afeb3f2 They’ll ask her to verify domain ownership and can help reset the MFA requirement so she can get back into her admin account.
Or, she can create a temporary trial Microsoft 365 Business account and use it to reach Microsoft Support directly through the admin center, that often helps connect with the right support team faster:
- Create a trial account here: https://www.microsoft.com/microsoft-365/business/microsoft-365-business-standard-one-month-trial
- Using the trial account, Sign in to Microsoft 365 admin center https://admin.microsoft.com
- Select Support > Help and support, enter question and select Contact support.
- She may cancel her trial subscription before the free trial period ends to stop future charges.
I really hope this information is helpful! Let me know if you have any further questions or concerns.
Regards,
John J.D.