To reset MySQL root password, stop MySQL
service mysql stop
Start MySQL with
mysqld_safe --skip-grant-tables
Start another terminal, login to MySQL as root
mysql -u root
Run following commands to change password.
update mysql.user set password=PASSWORD("PASSWORD_HERE") where User='root';
flush privileges;
quit
Now you need to kill running MySQL processes and start MySQL as normal.
killall mysqld_safe
killall mysqldRestart MySQL
service mysql start