Hey there! Nice to meet you!
If I may ask, may I have the exact error message upon using the authenticator?
Do you have access to the security information/verification methods, phone, or email address linked to the account?
Do you see any unfamiliar email addresses/phone numbers upon signing in to your account?
Did you have two-factor authentication (2FA) active on the account? If yes, do you still have the 25-character recovery codes?
Lastly, may I know when was the last time you successfully signed in to your Microsoft account?
Best regards,
Darhyl