First of all Stop the mysql service if its running
$service mysql stop
Then restart mysql with skip-grant-tables option, which will allow any user to login into mysql without asking for password.
Now login into mysql without password
$mysql –user=root mysql
You can now update the password of root user and flush priviledges.
mysql>update user set Password=PASSWORD(‘new-password’) where user=’root’;
At last you have to stop mysqld and start mysql. For this you need to find the Process ID of mysqld services
$ps ax | grep mysqld
you get two process with name mysqld and mysqld_safe
Kill both the process with the
$kill -9 <mysqld process id>
$kill -9 <mysqld_safe process id>
Now Restart Mysql
$service mysql start