http://www.rackspace.com/knowledge_center/article/mysql-resetting-a-lost-mysql-root-password
sudo /etc/init.d/mysql stop
sudo mysqld_safe --skip-grant-tables &
mysql -uroot
use mysql;
update user set password=PASSWORD("mynewpassword") where User='root';
flush privileges;
quit
sudo /etc/init.d/mysql stop && sudo /etc/init.d/mysql start
mysql -u root -p