Schlabo's Scripts use a strong encryption-algorithm, decrypting your password would take several years. So if you really forgot your password, you'll have to reset the users and create a new one.
Download config.pl, open it in a text-editor, scroll down to the bottom and change the corresponding lines to:
@user_names = ("");
Now you have to tell the scripts to crypt the empty password and create a default user. To do that call admin.pl like that:
The scripts will check if there is no user and will generate a default user without password and username. After that you can log in, go to the user management, edit the empty user to give it a username and password again.
This procedure may sound complicated, but it can be done in a few minutes. That's the price of high security-standards.