Well the admin config file is located in /admin_folder/includes/configure.php and your looking for the lines. The lines are close to the bottom of the conf.
// define our database connection
define('DB_TYPE', 'mysql');
define('DB_PREFIX', 'zen_');
define('DB_SERVER', 'localhost');
define('DB_SERVER_USERNAME', 'root'); <<<< remove
define('DB_SERVER_PASSWORD', ''); <<<<< remove
define('DB_DATABASE', ''); <<<< remove
define('USE_PCONNECT', 'false');
define('STORE_SESSIONS', 'db');
Towards the top of the config file you will see
define('DIR_WS_ADMIN', '/admin/'); <<< remove
define('DIR_WS_CATALOG', '/');
define('DIR_WS_HTTPS_ADMIN', '/admin/'); << remove
define('DIR_WS_HTTPS_CATALOG', '/');
With these ones make sure that what is listed is the same as the admin folder. For example if your admin folder was /zen but it has /zen23333 in there that could cause it to not work.
If you want to the other config file is located in /includes in your main directory.
The url for the admin site is showing 404 not found. And thinking about it posting it is not a good idea and it will show people where it is at and the whole point of zen cart having you change it is so that people don't know where its at.
If you are unable to find it re-post and I will see if I can give you a little more specific details. You will need to FTP into the server and find the config file that way.