I accidentally denied a notification on the authenticator app, and now I can't log in.
Answer
If you tap "No, it's not me" when prompted to verify your identity in the Microsoft Authenticator app, your account will be locked and you will no longer be able to log in.
To unlock your account, you will need to contact the eHelp Center. Please be prepared to provide personal information, such as your date of birth or physical address, to verify your identity.