If you're a Super Administrator in Joomla 3.0 and for some reason have lost, or forgotten your Administrator password to gain access to the backend of your website, there is a solution.
You can use phpMyAdmin to manually reset your password within the database.
By the way, this isn't a guide to hacking into anyone's Joomla site, you'll need to have hosting access to be able to edit the MySQL database (where all the passwords are stored).
Log in to your cPanel Control Panel
Scroll down untill you see the Database section. There you will see the link to "phpMyAdmin" click this link to open.
Once logged in, in the left menu click the name of your Joomla 3.0 database. In the left menu, click the table named similar to _users. For example, if you have a table prefix of 05lir, find the table named 05lir_users and click on it.
Find the Super User account in the list, and then click Edit next to it.
Next to password, in the drop down menu select MD5 (MD5 is an encryption method).
Once yu have selected MD5 clear the password field and type a new password for your username.
You have successfully reset your Joomla 3.0 Super User password using phpMyAdmin. You should now be able to log into your Joomla 3.0 administration.