You need to pass an array to WP_Query like this
then after you’ve ended the query use this to reset the query data.
<?php wp_reset_query(); ?>
example of standard query using WP_Query
$arg = array(
'posts_per_page' => 20
);
$query = new WP_Query($args)
//start to loop your things here
<?php if ($query->have_posts()) : ?>
<?php while ($query->have_posts()) : $query->the_post(); ?>
// your custom code here
endif; endwhile;