How to change root password for mysql and phpmyadmin

It depends on your configuration. Follow the instruction below to reconfigure phpmyadmin, and reset MySQL password.

1. Ctrl + Alt + T to launch terminal
2. sudo dpkg-reconfigure phpmyadmin
3. Connection method for MySQL database for phpmyadmin: unix socket
4. Name of the database's administrative user: root
5. Password of the database's administrative user: mysqlsamplepassword
6. MySQL username for phpmyadmin: root
7. MySQL database name for phpmyadmin: phpmyadmin
8. Web server to reconfigure automatically: apache2
9. ERROR 1045
10. ignore
11. sudo dpkg-reconfigure mysql-server-5.5
12. New password for the MySQL "root" user: mysqlsamplepassword
13. Repeat password for the MySQL "root" user: mysqlsamplepassword
14. After all this run following command on terminal to secure your mysql server. sudo mysql_secure_installation
15. Enter current password for root (enter for none): mysqlsamplepassword
16. Change the root password? [Y/n] n
17. Remove anonymous users? [Y/n] y
18. Disallow root login remotely? [Y/n] y
19. Remove test database and access to it? [Y/n] y
20. Reload privilege tables now? [Y/n] y

Wish it helps!

Thanks