rest mysql root password in ubuntu?

sudo /etc/init.d/mysql stop
sudo mkdir /var/run/mysqld/
sudo chown mysql /var/run/mysqld/
sudo mysqld_safe --skip-grant-tables &
sudo mysql -u root
use mysql;
update user set authentication_string=PASSWORD("New_Passwore_Here") where User='root';

flush privileges;
exit;

sudo /etc/init.d/mysql stop
sudo /etc/init.d/mysql start

sudo mysql -u root -p

Enjoy !