I had to use global $post;
Final code:
<?php
global $post;
$args = array(
'post_type' => 'attachment',
'numberposts' => -1,
'post_status' => null,
'post_parent' => $post->post_parent,
'order_by' => 'menu_order',
'order' => 'ASC'
);
$attachments = get_posts($args);
if ($attachments) {
echo '<div id="gallery-1" class="gallery galleryid-3105 gallery-columns-5 gallery-size-thumbnail">';
foreach ($attachments as $attachment) {
echo '<dl class="gallery-item">';
echo '<dt classs="gallery-icon">';
$large = wp_get_attachment_image_src($attachment->ID, 'large');
$thumb = wp_get_attachment_image($attachment->ID, 'thumbnail');
echo '<a href="' . $large[0] . '" rel="shadowbox[sbalbum-3105];player=img;">' . $thumb . '</a>';
echo '</dt>';
echo '</dl>';
}
echo '</div>';
}
?>