Sounds like something went wrong with the restore. Another possibility is to try to sign in to your account but select the Sign in another way link (assumes another way was set up) on the Two-factor verification page.
https://support.microsoft.com/en-us/account-billing/common-problems-with-two-step-verification-for-a-work-or-school-account-63acbb9b-16a1-47b9-8619-6a865e8071a5
otherwise, you may need to get the school admins to reset the account so you can setup the autherneticator again.
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