Return category posts with WP_Query

By default WP_Query will return only the post post type. To retrieve other post types, you need to add a post_type argument. Using any will return results from all public, registered post types.

$my_query = new WP_Query(
  array(
    'cat' => 1,
    'post_type' => 'any'
  )
); 
var_dump($my_query->request); // debug; allows you to see the SQL
if($my_query->have_posts()) {   
  // ..
}

If you only want a particular post type, just use the post type’s slug, or you can use an array of post type slugs to get returns from multiple particular post types.

Also, there is rarely a good reason to clobber $wp_query, even if you save it to put it back later.