Processes in Microsoft 365 for setting up Office apps, redeeming product keys, and activating licenses.
Did you recently changed your phone, or reinstalled your authenticator?
The problem is, this new phone / new authenticator isn't the one you authorized.
Microsoft requires your old authenticator before it will allow you to make any changes or add a new phone/authenticator.
These are the alternative ways that might be available to you - If you still have the old phone, then use the authenticator on the old phone. Else
- If you have a second admin, get the second admin to reset your account
- If you purchased from a reseller, ask the reseller, via delegated admin, to reset your account
- See if you can authenticate via SMS
If method 1-3 doesn't work for you, have a read on #4, on how to contact the data protection team.
Regards