To display the post order by modified date in wordpress
You should use DESC for order.
Try this:
$the_query = new WP_Query( array( 'post_type' => $post_type, 'numberposts' => '2', 'orderby' => 'modified', 'order' => 'DESC', ));Using DESC will give you the latest post first(descending order).
EDIT:
As Andrew commented, the default value for order is DESC and can thus be omitted from the code:
$the_query = new WP_Query( array( 'post_type' => $post_type, 'numberposts' => '2', 'orderby' => 'modified', ));