problems to add another account since i changed from phones (the other one was lost and its unrecoverable)

Your university’s IT help desk must reset your MFA registration unless Sign in another way offers a verification method you can still use.

Try an existing alternative first

1. Start signing in to the institutional account.
2. On the verification screen, select Sign in another way or I can’t use my Microsoft Authenticator app right now.
3. If offered, use a previously registered SMS/phone method, security key, passkey, or another Authenticator device.
4. After signing in, open Security info, add Authenticator on the new phone, test it, and then remove the lost device.

Microsoft recommends either signing in through another method or asking the organization’s help desk to clear the settings when a registered device is lost.^1^

If no alternative method works

Contact the university IT/help-desk team immediately and send this request:

I lost the phone registered for Microsoft Authenticator and have no usable alternative verification method. Please reset my MFA methods or require MFA re-registration for my institutional account so I can register Authenticator on my new phone. I need urgent access for an exam.

This cannot be fixed by reinstalling Authenticator or repeatedly adding the account. Work or school credentials are not transferred through Authenticator backup; only the account name is restored, and the account must be registered again.^2^

Give the following administrator procedure to the help desk:

1. Sign in to the Microsoft Entra admin center as at least an Authentication Administrator.
2. Go to Entra ID → Users.
3. Select the affected student account.
4. Open Authentication methods.
5. Select Require re-register MFA.
6. If the phone was lost, also select Revoke sessions.

Require re-register MFA removes registered phone numbers, Microsoft Authenticator registrations, and software OATH tokens. At the next sign-in, the account is prompted to configure MFA again.^3^

The administrator may instead provide a Temporary Access Pass if that recovery method is enabled by the university, allowing the new phone to be registered without approval from the lost device.^4^

After IT completes the reset:

1. Sign in again with the institutional account.
2. Follow the prompt to configure Microsoft Authenticator.
3. In Authenticator, choose Add account → Work or school account → Scan QR code.
4. Complete the test approval.
5. Add a second authentication method if university policy permits it.

Microsoft forum staff and ordinary Microsoft customer support cannot directly change a university-managed account; its authentication methods are controlled by the institution. For today’s exam, contact the university help desk and the instructor/exam office in parallel so they can document the access problem or provide an academic contingency.

References

1. Common problems with two-step verification for a work or school account
2. Transfer Microsoft Authenticator account entries to a new phone
3. Manage user authentication methods for Microsoft Entra multifactor authentication
4. How can I regain access to my account after losing access to Microsoft Authenticator? - Microsoft Q&A