Reset MySQL root password in LAMPP server on Ubuntu
The skip-grant-tables solution is not a recommended one, for a couple of reasons:


It makes the database vulnerable (even with skip-networking)
It requires taking your database down twice.


A solution which requires taking the database down just once is as follows:


Create a temporary SQL text file, say /tmp/init.sql
Within this file, write: 

SET PASSWORD FOR root@localhost = PASSWORD('the_new_password');
Add the following to your MySQL config file (on Ubuntu this is on /etc/mysql/my.cnf), under the [mysqld] section:

init-file=/tmp/init.sql
Restart MySQL once. The init file is read and executed upon startup. The password is reset.
Proceed to remove the init-file=/tmp/init.sql entry from my.cnf (do not forget this). Even as the server is up and running.
Remove the /tmp/init.sql file.


There are even more solutions! Please refer to a past blog post of mine. Make sure to check out comment #4 by strcmp