Thanks for your question.
Losing the MFA app requires you having to contact the admins of the accounts in question for work or school accounts.
You will need to contact the support teams of those applications to assist you in resetting your credentials or reach out to support https://support.microsoft.com/en-us/topic/customer-service-phone-numbers-c0389ade-5640-e588-8b0e-28de8afeb3f2
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Regards,
Abiola