If you have access to your configuration.php file for the Joomla installation on your server, can recover the password using the following method.
1.) Using an FTP program connect to your site. Find the configuration.php file and look at the file permissions. If the permissions are 444 or some other value, then change the permissions of the configuration.php file to 644. This will help prevent issues when uploading the changed configuration.php file later in this process.
2.) Download the configuration file.
3.) Open the configuration.php file that was downloaded in a text editor such as notepad++ and add this line
to the bottom of the list where myname is a username with administrator access that you know the password for. An username that is Author level or higher can also be used in place of a username with administrator access.
4.) Save the configuration.php file and upload it back to the site. You may leave the permissions on the configuration.php file at 644.
This user will now be a temporary super administrator.
5.) Login to the back end and change the password of the administrator user you don’t have the password for or create a new super admin user. If you create the new user you may want to block or delete the old user depending on your circumstances.
6.) When finished, make sure to use the “Click here to try to do it automatically” link that appears in the alert box to remove the line that was added to the configuration.php file. If using the link was not successful, then go back and delete the added line from your configuration.php file using a text editor. Upload the configuration.php file back to the site.
7.) Using your FTP program verify the file permissions of the configuration.php file, they should be 444. If you manually removed the added line, then change the file permissions on the configuration.php file to 444.
If you have no users who know their passwords and you can’t utilize front end registration you may need to make a change in your database as outlined below in this document.