How do I get content of custom post type through post ID in wordpress

Have a look at the Post & Page Parameters Section in the WP_Query Documentation

For getting a Post by Post ID, you need to use this:

$my_query = new WP_Query('post_type=movie_reviews&p=244');

If you only need the content of one specific post, you can also do this:

$mypost = get_post(244);
echo apply_filters('the_content',$mypost->post_content);

In this case, you don’t need to worry about the loop or the global vars getting overwritten, removing your main loop.