wp pagination dont show in homepage

Now i tried to go pdf-market.ir/?paged=2 but it’s show 404 Error !
check site, site search

i 1day tried to solve this problem but don’t succed.
my codes for loop in index.php

<ul class="page_result">
              <?php
              //$paged = (get_query_var('page')) ? get_query_var('page') :  1;
        $args = array(
            'post_type' => 'product',
            'stock' => 1,
            'posts_per_page' => 16,
            'orderby' => 'date',
            'order' => 'DESC',
            'paged' => 1,
            );
        $loop = new WP_Query( $args );
        while ( $loop->have_posts() ) : $loop->the_post(); global $product;   ?>
          <div class="bookbox">
              <a id="id-<?php the_id(); ?>" href="<?php the_permalink(); ?>" title="<?php the_title(); ?>">
            <div class="bookbox-img">
               <?php if (has_post_thumbnail( $loop->post->ID )) echo get_the_post_thumbnail($loop->post->ID, 'shop_catalog'); else echo '<img src="'.woocommerce_placeholder_img_src().'" alt="Placeholder" style="margin-left: -20px" width="200px" height="200px" />'; ?>
               </div>
              </a>
              <div class="bookbox-bookname"><a data-tooltip="<?php the_title(); ?>" class="bookname tooltip" href="<?php the_permalink(); ?>"><?php the_title(); ?></a></div>
                        <?php $mid_var = get_post_meta($post->ID, 'پدیداورنده',true);
            if(isset($mid_var) && !empty($mid_var)) : ?>
              <div class="bookbox-dtibook"><span class="garyYekan10">پدیدآورنده:</span> 
            <?php echo get_post_meta($post->ID, 'پدیداورنده',true); ?>
             </div><?php endif; ?>
                    <?php $mid_var = get_post_meta($post->ID, 'ناشر',true);
            if(isset($mid_var) && !empty($mid_var)) : ?>
              <div class="bookbox-dtibook"><span class="garyYekan10">ناشر: </span>
            <?php echo get_post_meta($post->ID, 'ناشر',true); ?>
              </div>
              <?php endif; ?>
                    <?php $mid_var = get_post_meta($post->ID, 'نوبت چاپ',true);
            if(isset($mid_var) && !empty($mid_var)) : ?>
              <div class="bookbox-dtibook"><span class="garyYekan10">نوبت چاپ:</span>
                <?php echo get_post_meta($post->ID, 'نوبت چاپ',true); ?>
              </div> 
            <?php endif; ?>
              <div class="bookbox-price"><span class="garytahoma8">قیمت: </span> <?php woocommerce_template_loop_price() ?> </div> 
                    <?php $mid_var = get_post_meta($post->ID, 'موجودی',true);
            if(isset($mid_var) && !empty($mid_var)) : ?>
              <div class="bookbox-price"><span class="garytahoma8">موجودی: </span><span class="fontgreen10">
            <?php echo get_post_meta($post->ID, 'موجودی',true); ?>
              </span> </div><?php endif; ?>
              <a alt="مشخصات کتاب" href="<?php the_permalink(); ?>"><div title="مشخصات کتاب" alt="مشخصات کتاب" class="bookbox-bookinfo"></div></a>
              <a alt="خرید کتاب" href="<?php the_permalink(); ?>&add-to-cart=<?php the_id(); ?>">
              <div alt="خرید کتاب" class="bookbox-addcart"></div>
              </a>


              </div>

        <?php endwhile; ?>
        <?php wp_reset_postdata(); ?>
</ul>   

<div class="pagination">
    <?php 
    wp_pagination(); ?>
</div>

and my code in function.php > pagination

<?php
function wp_pagination() {
    global $wp_query;
    $big = 12345678;
    $page_format = paginate_links( array(
        'base' => str_replace( $big, '%#%', esc_url( get_pagenum_link( $big ) ) ),
        'format' => '?paged=%#%',
        'current' => max( 1, get_query_var('paged') ),
        'total' => $wp_query->max_num_pages,
        'type'  => 'array'
    ) );
    if( is_array($page_format) ) {
                $paged = ( get_query_var('paged') == 0 ) ? 1 : get_query_var('paged');
                echo '<div><ul>';
                foreach ( $page_format as $page ) {
                        echo "<li>$page</li>";
                }
               echo '</ul></div>';
    }
}
?>

this is all…
in searches and archives is show pagination but
in home page and example:site.com dont show pagination and it’s place just free and no code…