First, check the password that is located in: /root/.my.cnf... This is usually the first root password the server was given once cpanel is installed. If that does not work, you will need to reset the mysqld root password.
First, stop the mysqld, usually: /etc/rc.d/init.d/mysql stop
Then stop chkservd to keep it from interfering with mysqld while you work on it with /etc/rc.d/init.d/chkservd stop
Now, we need to start up mysqld, but, without the grant tables:
Run: mysqld --skip-grant-tables -u mysql &
After it's started, it's time to change the password. Run the following three commands:
mysql -u root mysql UPDATE user SET Password=PASSWORD('new_password') WHERE user='root'; FLUSH PRIVILEGES;
Now you just killall -9 mysqld and start it up normally with its safe_mysqld script.