Hello, Really need help !!

I altered the Tell_friend_php in order to have it in every page (10 days ago) then I changed my mind, tried to alter it again in order to have it only where it supposed to be. The problem now is that I forgot what I did (I very new to PHP), The box it is not in any page even if in the Layout Boxes Controller it is set to "ON". Here is the tell_a friend_php code just in case you are able that something is wrong:

// test if box should display
$show_tell_a_friend= false;
if (isset($_GET['product_id']) and zen_products_id_valid($_GET['product_id'])) {
if (!($_GET['main_page']==FILENAME_TELL_A_FRIEND)) $show_tell_a_friend = true;
}
if ($show_tell_a_friend == true) {
require($template->get_template_dir('tpl_tell_a_friend.php',DIR_WS_TEMPLATE, $current_page_base,'sideboxes'). '/tpl_tell_a_friend.php');
$title = BOX_HEADING_TELL_A_FRIEND;
$title_link = false;
require($template->get_template_dir($column_box_default, DIR_WS_TEMPLATE, $current_page_base,'common') . '/' . $column_box_default);
}
Thanks a lot

Mario