Fatal error: Call to undefined function mantra_content_nav()

I was checking out my website today, and noticed that when I click on the Home page, I get this:

<b style=”font-family: ‘Segoe UI’, Arial, sans-serif; background-color: #ffffff; border: 0px; margin: 0px; padding: 0px; vertical-align: baseline; font-size: 16px; line-height: 24px;”>Fatal error</b><span style=”font-family: ‘Segoe UI’, Arial, sans-serif; font-size: 16px; line-height: 24px; background-color: #ffffff;”>: Call to undefined function mantra_content_nav() in</span><b style=”font-family: ‘Segoe UI’, Arial, sans-serif; background-color: #ffffff; border: 0px; margin: 0px; padding: 0px; vertical-align: baseline; font-size: 16px; line-height: 24px;”>/home/brimoo20/armchairanglophile.com/wp-content/themes/mantra/index.php</b><span style=”font-family: ‘Segoe UI’, Arial, sans-serif; font-size: 16px; line-height: 24px; background-color: #ffffff;”> on line </span><b style=”font-family: ‘Segoe UI’, Arial, sans-serif; background-color: #ffffff; border: 0px; margin: 0px; padding: 0px; vertical-align: baseline; font-size: 16px; line-height: 24px;”>26</b>

What on earth happened here? Is this because of the update I did the other day to the Mantra theme? I don’t think I’ve messed around in index.php, but here’s what it looks like:

<?php

/**

* The main template file.

*

* This is the most generic template file in a WordPress theme

* and one of the two required files for a theme (the other being style.css).

* It is used to display a page when nothing more specific matches a query.

* E.g., it puts together the home page when no home.php file exists.

* Learn more: http://codex.wordpress.org/Template_Hierarchy

*

* @package Cryout Creations

* @subpackage Mantra

*/

get_header();

if ($mantra_frontpage==”Enable” && is_front_page() ) {

mantra_frontpage_generator();

}

else {

?>

<section id=”container”>

<div id=”content” role=”main”>

<?php cryout_before_content_hook(); ?><?php if ( have_posts() ) : ?>

<?php mantra_content_nav( ‘nav-above’ ); ?>

<?php /* Start the Loop */ ?>

<?php while ( have_posts() ) : the_post(); ?>

<?php get_template_part( ‘content’, get_post_format() ); ?>

<?php endwhile; ?>

<?php if($mantra_pagination==”Enable”) mantra_pagination(); else mantra_content_nav( ‘nav-below’ ); ?>

<?php else : ?>

<article id=”post-0″ class=”post no-results not-found”>

<header class=”entry-header”>

<h1 class=”entry-title”><?php _e( ‘Nothing Found’, ‘mantra’ ); ?></h1>

</header><!– .entry-header –>

<div class=”entry-content”>

<p><?php _e( ‘Apologies, but no results were found for the requested archive. Perhaps searching will help find a related post.’, ‘mantra’ ); ?></p>

<?php get_search_form(); ?>

</div><!– .entry-content –>

</article><!– #post-0 –>

<?php endif; ?><?php cryout_after_content_hook(); ?>

</div><!– #content –>

<?php get_sidebar(); ?>

</section><!– #container –>

<?php } // else

get_footer(); ?>

Please, how can I fix this and get my homepage back? I can’t have a website with this as the homepage!