How to use WP_Query with have_posts()?
global $wp_query;
$original_query = $wp_query;
$wp_query = null;
$wp_query = new WP_Query( $args );
if ( have_posts() ) :
while ( have_posts() ) : the_post();
the_title();
the_excerpt();
endwhile;
else:
echo ‘no posts found’;
endif;
$wp_query = null;
$wp_query = $original_query;
wp_reset_postdata();