Check the account identifier, password and keyboard layout before resetting anything. Extra spaces copied with a password can matter.
Use the password-recovery route if you no longer know the password. Do not create another profile just to regain access.
A current authenticator code depends on the device clock. Automatic date and time can resolve codes rejected because of clock drift.
A lost authenticator is different from a forgotten password: use the account-recovery process for the missing second factor.
If the site loads but the account is restricted or awaiting verification, changing the domain does not remove that requirement.
Keep the exact error message for support; it is more useful than repeatedly pressing the sign-in button.