A Microsoft app for iOS and Android devices that enables authentication with two-factor verification, phone sign-in, and code generation
If you did not setup alternate MFA options, then you need to have an account reset done by the account owner. This is different for each account type. Try the forgot password flow at signin.
Here are the instructions for a Microsoft account
Note: you will need to prove your are the account owner and recovery after proof takes 30 days (this for security as email notifications are sent to the owner to allow cancellation)