How to show other custom post type other than current post type in a single.php

Question

You will need to do a wp_query to get the other post types into your file e.g.

<?php
     $args = array(
      'post_type' => 'posttype_name',
      'posts_per_page' => '-1',
      'order' => 'DESC'
     );
     $query = new WP_Query($args);
     while ( $query->have_posts() ) {
      $query->the_post();
          the_title();
     }
     wp_reset_postdata();
     ?>