So you somehow lost the adminstration or login password to your php script? Chances are the password is stored encrypted inside some database table on the server.
You will need to use phpmyadmin inside your cPanel control panel, go to the database for that script and find the particular table which has the password stored. The developer of the script, or a google search will help you find the name of the table. Since it will likely be stored encrypted, you will not be able to simply read it! But you can generate a new md5 password here and paste the result in place of the old password.
For example, when you finally find the table holding the password, it will look something like this - 9c0a218672f4235642b290a8498e8ce0
Simply generate a new md5 password here, and replace it and save.
More information:
http://docs.joomla.org/How_you_reset_an_administrator_password%3F
