nav_link not showing at all

The code <?php posts_nav_link(); ?> is showing no text at all at the bottom of my most recent posts. If I past it above <?php endwhile; else: ?> it will show and work below each post but if I move it below <?php endwhile; else: ?> so it will only show once at the bottom it won’t show up at all.

Can someone please give me some advice?

<div id="wrapper">
<div id="main">

  <div id="content">

    <?php if (have_posts()) : while (have_posts()) : the_post(); ?>
    <p id="posthead"><a href="<?php the_permalink();?>" ><?php the_title(); ?></a>
   </p>
    <p id="postdate">Posted on <?php the_time('F jS, Y') ?></p>
    <p><?php the_content(__('(more...)')); ?></p>
    <p id="categories"><strong>Categories:</strong>?<?php the_category(','); ?> </p>

    <p id="commentlink"><a href="<?php the_permalink();?>" ><?php comments_number(); ?></a>

    </p><p>?</p>

        <hr><p>?</p>
        <?php endwhile; else: ?>
  <?php posts_nav_link(); ?>

         <p><?php _else('Sorry, no posts matched your criteria.'); ?></p>
<p>?</p>

    <?php endif; ?>
    <script type="text/javascript">stLight.options({publisher: "352b69ee-ce5f-4135-a517-2cfe778dc258", doNotHash: false, doNotCopy: false, hashAddressBar: true});</script>
<script>
var options={ "publisher": "352b69ee-ce5f-4135-a517-2cfe778dc258", "position": "left", "ad": { "visible": false, "openDelay": 5, "closeDelay": 0}, "chicklets": { "items": ["facebook", "twitter", "linkedin", "stumbleupon", "pinterest", "email", "sharethis"]}};
var st_hover_widget = new sharethis.widgets.hoverbuttons(options);
</script>
  </div>

  <?php get_sidebar(); ?>

</div>

Link to me site: https://sofafrog.com/