Gravatar does’t show

Can you post the code from your theme’s comments.php

Either inside backticks or in a pastebin.
https://wordpress.pastebin.com/

<?php if ( !empty($post->post_password) && $_COOKIE['wp-postpass_' . COOKIEHASH] != $post->post_password) : ?>
<p><?php _e('Enter your password to view comments.'); ?></p>
<?php return; endif; ?>

<h2 id="comments"><?php comments_number(__('No Comments'), __('1 Comment'), __('% Comments')); ?>
<?php if ( comments_open() ) : ?>
	<a href="#postcomment" title="<?php _e("Leave a comment"); ?>">&raquo;</a>
<?php endif; ?>
</h2>

<?php if ($comments) : ?>
<div id="commentwrap">
 <ol class="commentlist">

 <?php foreach ($comments as $comment) : ?>

  <li class="<?=$oddcomment;?>">
   <img border="0" style="padding:1px; float:left; margin:0px 10px 5px 0px; border:1px solid #ccc;" alt="avatar" src="<?php gravatar("R", 48, get_option('home')."/wp-content/themes/Simplism/images/avatar.gif"); ?>" />

   <a name="comment-<?php comment_ID() ?>"></a><cite><?php comment_author_link() ?></cite> Says:<br />

   <div class="comment-inside">
   <small class="commentmetadata"><a href="#comment-<?php comment_ID() ?>" title=""><?php comment_date('F jS, Y') ?> at <?php comment_time() ?></a> <?php edit_comment_link('e','',''); ?></small>

   <?php comment_text() ?>
   </div>
</li>

 <?php endforeach; ?>

 </ol>
<div style="clear: both;"></div>
</div>

<?php else : // If there are no comments yet ?>
	<p><?php _e('No comments yet.'); ?></p>
<?php endif; ?>

<p><?php post_comments_feed_link(__('<abbr title="Really Simple Syndication">RSS</abbr> feed for comments on this post.')); ?>
<?php if ( pings_open() ) : ?>
	<a href="<?php trackback_url() ?>" rel="trackback"><?php _e('TrackBack <abbr title="Universal Resource Locator">URL</abbr>'); ?></a>
<?php endif; ?>
</p>

<?php if ( comments_open() ) : ?>
<h2 id="postcomment"><?php _e('Leave a comment'); ?></h2>

<?php if ( get_option('comment_registration') && !$user_ID ) : ?>
<p><?php printf(__('You must be <a href="%s">logged in</a> to post a comment.'), get_option('siteurl')."/wp-login.php?redirect_to=".urlencode(get_permalink()));?></p>
<?php else : ?>

<form action="<?php echo get_option('siteurl'); ?>/wp-comments-post.php" method="post" id="commentform">

<?php if ( $user_ID ) : ?>

<p><?php printf(__('Logged in as %s.'), '<a href="'.get_option('siteurl').'/wp-admin/profile.php">'.$user_identity.'</a>'); ?> <a href="<?php echo get_option('siteurl'); ?>/wp-login.php?action=logout" title="<?php _e('Log out of this account') ?>"><?php _e('Log out &raquo;'); ?></a></p>

<?php else : ?>

<p><input type="text" name="author" id="author" value="<?php echo $comment_author; ?>" size="22" tabindex="1" />
<label for="author"><small><?php _e('Name'); ?> <?php if ($req) _e('(required)'); ?></small></label></p>

<p><input type="text" name="email" id="email" value="<?php echo $comment_author_email; ?>" size="22" tabindex="2" />
<label for="email"><small><?php _e('Mail (will not be published)');?> <?php if ($req) _e('(required)'); ?></small></label></p>

<p><input type="text" name="url" id="url" value="<?php echo $comment_author_url; ?>" size="22" tabindex="3" />
<label for="url"><small><?php _e('Website'); ?></small></label></p>

<?php endif; ?>

<!--<p><small><strong>XHTML:</strong> <?php printf(__('You can use these tags: %s'), allowed_tags()); ?></small></p>-->

<p><textarea name="comment" id="comment" cols="100%" rows="10" tabindex="4"></textarea></p>

<p><input name="submit" type="submit" id="submit" tabindex="5" value="<?php echo attribute_escape(__('Submit Comment')); ?>" />
<input type="hidden" name="comment_post_ID" value="<?php echo $id; ?>" />
</p>
<?php do_action('comment_form', $post->ID); ?>

</form>

<?php endif; // If registration required and not logged in ?>

<?php else : // Comments are closed ?>
<p><?php _e('Sorry, the comment form is closed at this time.'); ?></p>
<?php endif; ?>