In case you have forgotten your root password for MySQL database, you can change it by first killing all mysql processes with:
killall mysql or /etc/init.d/mysql stop (for Debian users)
Now you have to start mysql again with this command:
mysqld --skip-grant-tables &
Then you can change your MySQL root user password with:
mysqladmin -u root flush-privileges password 'newpassword'
And now you have to stop mysql again with:
killall mysqld
After this you can start your MySQL normaly with your usual command like:
/etc/initd/mysql start
That’s it, simple but realy usefull trick…