Quick note in case you are not aware of this. The system root user and the MySQL root user are two entirely different accounts and passwords. Even though they are both called root the MySQL password is stored in the application and the system root password is stored in /etc/shadow. The system root user does not have root privleges in MySQL and the MySQL root user does not have system root privdgles.
If you were already aware of this then either you have the wrong password for root or the host is incorrect. If you have never set a root password for MySQL server, the server does not require a password at all for connecting as root. To setup root password for first time, use mysqladmin command at shell prompt as follows:
mysqladmin -u root password NEWPASSWORD
You could try email@example.com or if you have system root access to the box then there is a procedure that allows you to reset MySQL root to what ever you want.
If you're in one of those predicaments where cls.__private attributes just aren't enough since they can easily be accessed through inst._cls__private, and you need something a little more secure, here's ...