Popular post

<?php
$popularpost = new WP_Query( array( 'posts_per_page' => 4, 'meta_key' => 'wpb_post_views_count', 'orderby' => 'meta_value_num', 'order' => 'DESC'  ) );
while ( $popularpost->have_posts() ) : $popularpost->the_post();

  ?>



Function.php
function wpb_set_post_views($postID) {
    $count_key = 'wpb_post_views_count';
    $count = get_post_meta($postID, $count_key, true);
    if($count==''){
        $count = 0;
        delete_post_meta($postID, $count_key);
        add_post_meta($postID, $count_key, '0');
    }else{
        $count++;
        update_post_meta($postID, $count_key, $count);
    }
}
//To keep the count accurate, lets get rid of prefetching
remove_action( 'wp_head', 'adjacent_posts_rel_link_wp_head', 10, 0);
function wpb_track_post_views ($post_id) {
    if ( !is_single() ) return;
    if ( empty ( $post_id) ) {
        global $post;
        $post_id = $post->ID;   
    }
    wpb_set_post_views($post_id);
}
add_action( 'wp_head', 'wpb_track_post_views');

function wpb_get_post_views($postID){
    $count_key = 'wpb_post_views_count';
    $count = get_post_meta($postID, $count_key, true);
    if($count==''){
        delete_post_meta($postID, $count_key);
        add_post_meta($postID, $count_key, '0');
        return "0 View";
    }
    return $count.' Views';
}