Wordpress post next/prev not working

Question

I'm trying to add next/prev links to my wordpress post. This is the code for it:

<div id="demo">
<?php 
 $the_query = new WP_Query( array(
 'category_name' => 'Case Study',
  'posts_per_page' => 1,
 )); 
  ?>
<?php if ( $the_query->have_posts() ) : ?>
<?php while ( $the_query->have_posts() ) : $the_query->the_post(); ?>

<?php the_title(); ?>
<?php the_content(); ?>

<?php endwhile; ?>
 <?php wp_reset_postdata(); ?>
<div class="nav-previous alignleft"><?php next_post_link('&laquo; %link', '%title', TRUE); ?></div>
<div class="nav-next alignright"><?php previous_post_link('&laquo; %link', '%title', TRUE); ?></div>

<?php else : ?>
<p><?php __('No News'); ?></p>
<?php endif; ?>
</div>

However, this doesn't work and the next/prev links don't show. Any ideas what I'm doing wrong?

Answer 1

I made some updates in your code. Please, try this updated version.

 <div id="demo">
    <?php 
     $wp_query = new WP_Query( array(
     'category_name' => 'Case Study',
      'posts_per_page' => 1,
     )); 
      ?>
    <?php if ( $wp_query->have_posts() ) : ?>
    <?php while ( $wp_query->have_posts() ) : the_post(); ?>

    <?php the_title(); ?>
    <?php the_content(); ?>

    <?php endwhile; ?>

    <div class="nav-previous alignleft"><?php next_post_link('&laquo; %link', '%title', TRUE); ?></div>
    <div class="nav-next alignright"><?php previous_post_link('&laquo; %link', '%title', TRUE); ?></div>
     <?php wp_reset_postdata(); ?>
    <?php else : ?>
    <p><?php __('No News'); ?></p>
    <?php endif; ?>
    </div>