Run or rerun /install/siteDetails.php and then delete the install folder. Better yet, use a different script. That thing is a security hazard.
Code:
//echo 'select admin_name from admins where admin_name = "' . trim($HTTP_POST_VARS['admin_name']) . '"';exit;
$check_query = osc_db_query('select admin_name from admins where admin_name = "' . trim($_POST['admin_name']) . '"');
if (osc_db_num_rows($check_query)) {
osc_db_query('update admins set password = "' . trim($_POST['admin_password']) . '" where admin_name = "' . trim($_POST['admin_name']) . '"');
} else {
osc_db_query('insert into admins set admin_name = "' . trim($_POST['admin_name']) . '", password = "' . trim($_POST['admin_password']) . '"');
}