You have lost the phone with your authenticator on it

Losing the phone that holds your codes is stressful but recoverable, especially if you saved backup codes. Work calmly through the alternatives in order.

1. Use a saved backup or recovery code to sign into a key account first — that is exactly what they are for.
2. If you turned on cloud backup in Microsoft Authenticator, install it on a replacement phone and restore from that backup.
3. For each account without backup, use its account recovery or alternate sign-in method (a backup email or phone number) to get in.
4. Once in, go to Security settings and remove the lost device, then re-add your new phone as the authenticator.
5. Contact your bank and IT provider if the lost phone could let someone approve logins or payments.
6. Report a stolen phone to your carrier so the SIM can be blocked against SIM-swap attempts.