user:root
#The password is empty
password:
#If by accident you set the password and you don't remember it
service mysql stop #Stop mysql service
mysqld_safe --skip-grant-tables & #disable "login"
mysql #Log in into mysql, you should see mysql> in prompt
UPDATE mysql.user SET Password=PASSWORD('new-password') WHERE User='root';
FLUSH PRIVILEGES; #
exit; # exit from mysql
mysqladmin -u root -p shutdown # shutdown mysql service
service mysql start # Restart your service