Add a “default sorting” menu to child store pages

Take a look at whether or not your theme has an archive-product.php file in the woocommerce folder. This is a copy of the WooCommerce category template (which is displayed by archive-product.php. As long as your template has the do_action( 'woocommerce_before_shop_loop' ); action hook then the woocommerce_catalog_ordering() function should automatically be called with a priority of 30… as it says directly in the code comments. Either your theme templates need to be updated for WooCommerce 2.0 or your theme has intentionally removed the woocommerce_catalog_ordering() function from the woocommerce_before_shop_loop.

<?php
/**
 * The Template for displaying product archives, including the main shop page which is a post type archive.
 *
 * Override this template by copying it to yourtheme/woocommerce/archive-product.php
 *
 * @author      WooThemes
 * @package     WooCommerce/Templates
 * @version     2.0.0
 */

if ( ! defined( 'ABSPATH' ) ) exit; // Exit if accessed directly

get_header('shop'); ?>

    <?php
        /**
         * woocommerce_before_main_content hook
         *
         * @hooked woocommerce_output_content_wrapper - 10 (outputs opening divs for the content)
         * @hooked woocommerce_breadcrumb - 20
         */
        do_action('woocommerce_before_main_content');
    ?>

        <?php if ( apply_filters( 'woocommerce_show_page_title', true ) ) : ?>

            <h1 class="page-title"><?php woocommerce_page_title(); ?></h1>

        <?php endif; ?>

        <?php do_action( 'woocommerce_archive_description' ); ?>

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

            <?php
                /**
                 * woocommerce_before_shop_loop hook
                 *
                 * @hooked woocommerce_result_count - 20
                 * @hooked woocommerce_catalog_ordering - 30
                 */
                do_action( 'woocommerce_before_shop_loop' );
            ?>

            <?php woocommerce_product_loop_start(); ?>

                <?php woocommerce_product_subcategories(); ?>

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

                    <?php woocommerce_get_template_part( 'content', 'product' ); ?>

                <?php endwhile; // end of the loop. ?>

            <?php woocommerce_product_loop_end(); ?>

            <?php
                /**
                 * woocommerce_after_shop_loop hook
                 *
                 * @hooked woocommerce_pagination - 10
                 */
                do_action( 'woocommerce_after_shop_loop' );
            ?>

        <?php elseif ( ! woocommerce_product_subcategories( array( 'before' => woocommerce_product_loop_start( false ), 'after' => woocommerce_product_loop_end( false ) ) ) ) : ?>

            <?php woocommerce_get_template( 'loop/no-products-found.php' ); ?>

        <?php endif; ?>

    <?php
        /**
         * woocommerce_after_main_content hook
         *
         * @hooked woocommerce_output_content_wrapper_end - 10 (outputs closing divs for the content)
         */
        do_action('woocommerce_after_main_content');
    ?>

    <?php
        /**
         * woocommerce_sidebar hook
         *
         * @hooked woocommerce_get_sidebar - 10
         */
        do_action('woocommerce_sidebar');
    ?>

<?php get_footer('shop'); ?>

Updated based on your template code:

Just because you are using WooCommerce 2.0 doesn’t mean that your theme’s templates were updated. I have had to do that for several clients. However, the action hook do_action( 'woocommerce_before_shop_loop' ); is present.

I would:

  1. verify whether it is in the markup (view source) and being hidden by CSS
  2. check all the functions for something that would remove the function: remove_action('woocommerce_before_shop_loop', 'woocommerce_catalog_ordering', 30);
  3. check all the function for a modified definition of woocommerce_catalog_ordering()
  4. rename the archive-product.php template to something else temporarily archive-productTEST.php so that WooCommerce will load it’s default template instead

Without access to your site/code that is about all I can suggest.