Hi,
I am sorry to hear for what happened, to recover administrator access for your Business Microsoft 365 account there are some steps you can do.
Try and follow this steps:
Using Global Admin recovery / Tenant Ownership
Submit a support request through the Microsoft 365 support page. Go to this website https://www.microsoft.com/en-us/microsoft-365/support
Click log in or access my tenant. For verification of your organization account you need to show the following information such as Domain ownership, Business Documentation or any supporting documents or information that will help to verify the account.
Or open this link: https://admin.microsoft.com/
log in using your previous Admin email account, If you're prompted to request admin access, follow the provided steps on the page.
For more information please check this article: https://learn.microsoft.com/en-us/industry/nonprofit/microsoft-for-nonprofits/access-tenant
I hope this information helps you move forward , If you need assistance please let us know.
Thank you so much
Best regards,
Jansher