How to add previous/next page links to blog

Hi there,

My theme doesn’t seem to have a previous/next page link, that would appear at the end of a page. I’ve been trying to find the solution to my problem and nothing seems to be working. My site is: https://muphoricsounds.com

The index.php file has the following:

<?php get_header(); ?>
<div class="contentLayout">
<div class="content">

<?php if (have_posts()) : ?>
<?php while (have_posts()) : the_post(); ?>
<div class="Post">
 <div class="Post-body"><p></p>
<div class="Post-inner">
<h2 class="PostHeaderIcon-wrapper"> <a href="<?php the_permalink() ?>" rel="bookmark" title="Permanent Link to <?php the_title_attribute(); ?>"><?php the_title(); ?></a>
</h2>
<?php if (!is_page()): ?>
<div class="PostMetadataHeader">
<img class="metadata-icon" src="<?php bloginfo('template_url'); ?>/images/PostDateIcon.png" width="18" height="18" alt="PostDateIcon"/> <?php the_time('F jS, Y') ?> | <img class="metadata-icon" src="<?php bloginfo('template_url'); ?>/images/PostAuthorIcon.png" width="14" height="14" alt="PostAuthorIcon"/> Author: <a href="#" title="author"><?php the_author() ?></a><?php edit_post_link('Edit', ' | '); ?>
</div>
<?php endif; ?>
<div class="PostContent">
<?php the_content('Read the rest of this entry &raquo;'); ?>

</div>
<?php if (!is_page()): ?>
<div class="PostMetadataFooter">
<img class="metadata-icon" src="<?php bloginfo('template_url'); ?>/images/PostCategoryIcon.png" width="18" height="18" alt="PostCategoryIcon"/> Category: <?php the_category(', ') ?> | <img class="metadata-icon" src="<?php bloginfo('template_url'); ?>/images/PostTagIcon.png" width="18" height="18" alt="PostTagIcon"/> <?php the_tags('Tags: ', ', ', ' '); ?> | <img class="metadata-icon" src="<?php bloginfo('template_url'); ?>/images/PostCommentsIcon.png" width="18" height="18" alt="PostCommentsIcon"/> <?php comments_popup_link('No Comments »', '1 Comment »', '% Comments »'); ?>
</div>
<?php endif; ?>

<?php if (is_single() &amp;&amp; !is_page()): ?>
<div class="navigation">
<div class="alignleft"><?php previous_post_link('&laquo; %link') ?></div>
<div class="alignright"><?php next_post_link('%link &raquo;') ?></div>
</div>
<?php comments_template(); ?>
<?php endif; ?>
<?php if (is_page()) edit_post_link('Edit this entry.', '<p>', '</p>'); ?>

</div>

 </div>
</div>

<?php endwhile; ?>
<?php else : ?>

<h2 class="center">Not Found</h2>
<p class="center">Sorry, but you are looking for something that isn't here.</p>
<?php endif; ?>

</div>
<div class="sidebar1">
<?php include (TEMPLATEPATH . '/sidebar1.php'); ?>
</div>
<div class="sidebar2">
<?php include (TEMPLATEPATH . '/sidebar2.php'); ?>
</div>

</div>
<div class="clear-float"></div>

<?php get_footer(); ?>

I’ve seen a few variations of what to use, and have tried to insert it with no success. Please could someone advise me where on the Index file the code should go – and what code would work best with this particular theme?

Thank you in advance for your help!