This is a quicker, less intrusive method with less downtime to reset mysql root password: Create the following file and then enter the command that follows

vim /var/lib/mysql/mysql.init

SET PASSWORD FOR 'root'@'localhost'=PASSWORD('mynewpassword');  

Now edit: /etc/my.cnf and enter the following under the [mysqld] block

init_file=/var/lib/mysql/mysql.init  

service mysqld restart  

mysql -u root -p  

Now delete the /var/lib/mysql/mysql.init and init_file=/var/lib/mysql/mysql.init line entered in /etc/my.cnf file

DONE