Please contact the Oracle Database Administrator (DBA) of the particular database server you are connecting to, and ask that person to provide you with the correct Oracle username / password OR ask that person to reset your Oracle username / password.
This would not be considered a Toad issue. Quest does not have access to its customer’s databases, so Quest would not be able to perform the above for you.
Also try logging in to SQL Plus. If the same error appears in SQL Plus, then it is a problem with the database or you are entering the wrong username or password.