Just checked your site, everything looks in place so let’s try something else. Please, open wordpress-popular-posts.php using a text editor such as Notepad or Dreamweaver, find this code (around line 624):
//echo "SELECT $wpdb->posts.ID, $wpdb->posts.post_title $fields FROM $wpdb->posts $join WHERE $wpdb->posts.post_status = 'publish' AND $wpdb->posts.post_password = '' AND $range $force_pv $nopages $exclude GROUP BY $wpdb->posts.ID ORDER BY $sortby DESC LIMIT " . $instance['limit'];
… and uncomment it:
echo "SELECT $wpdb->posts.ID, $wpdb->posts.post_title $fields FROM $wpdb->posts $join WHERE $wpdb->posts.post_status = 'publish' AND $wpdb->posts.post_password = '' AND $range $force_pv $nopages $exclude GROUP BY $wpdb->posts.ID ORDER BY $sortby DESC LIMIT " . $instance['limit'];
Save changes. Then, a line of code should show on your homepage, right before the “Sorry, no data so far” text. Get a screenshot of that and email it to me: hcabrerab at gmail so I can see the output. Oh, remember to comment back that line of code as well!