How to reactivate my authenticator

Hello, thank you for reaching out to Microsoft Q&A.

If you have accidentally uninstalled the Authenticator app on your device, or performed a factory reset on your mobile, or changed your mobile device, and want to link your account to the Authenticator app again, you will need to follow the steps here.

1. Open/Install the Authenticator app on your device again.
2. Then, select 'Begin Recovery' or 'Restore from backup' on the screen.
3. Enter the recovery email address and Password.
4. You'll be prompted to verify your identity through the Authenticator app.
5. Select "I can't use the Authenticator app right now" or choose "Show more verification methods."
6. You can then use alternative verification methods, such as your phone number or email address, to confirm your identity.

Sometimes you may be prompted to reset your password. After the reset, select "Start Recovery" again and add your account to the Authenticator app.

All of your previously added accounts will be linked to your Microsoft Authenticator app again, and you'll need to verify each account next.

Reference:

Restore Microsoft Authenticator account credentials-

Restore account credentials from Microsoft Authenticator

Let me know if you still need more help.