I just installed Plogger, and everything went fine except I came to the admin login page, and I never set a admin user name or password, and I can't find a default one anywhere.
Also, if all else fails you can access the database via phpmyadmin or other system. open the plogger_config table and edit the admin_password field. You will need to use a MD5 hash generator http://www.adamek.biz/md5-generator.php to find what string to enter into the field for what password you want to use. Change the hash and you should be able to login fine.