For the issue with thumbnail not showing up, this is the error :
<p>You don't have permission to access /6yhn5tgb/wp-content/plugins/category-grid-view-gallery/includes/timthumb.php
on this server.</p>
<p>Additionally, a 404 Not Found
error was encountered while trying to use an ErrorDocument to handle the request.</p>
If the thumbnails aren't showing anywhere, then here are a few reasons why:
- If you are using WordPress Multisite, try replacing /scripts/timthumb.php with the one from here: http://compu.terlicio.us/2011/04/timthumb-for-wordpress-multisite/ The theme is already taking into account Multisite, but still some may have issues which this timthumb.php update may hopefully resolve.
- Make sure your image filename (or path) has no unusual characters in it. Tildes (~) is a common character used in filenames which timthumb.php doesn't seem to agree with.
- Make sure you're NOT running PHP 4.x. If you are, upgrade to 5.x. This was a solution to someone recently who tried EVERYTHING and images weren't showing up. A way to find out what version you're running is to add this code to one of your theme files, like in header.php: <?php phpinfo; ?> Make sure it's somewhere between the <body> tag. Refresh the site and you'll see a really ugly table that's hard to read, but you'll be able to find out the version of PHP you're using.
To upgrade to PHP 5, contact your web host company.
Check out this page, made by the creator of Timthumb. It contains many troubleshooting tips which may help: http://www.binarymoon.co.uk/2010/11/timthumb-hints-tips/
You can troubleshoot TimThumb more from here
Due to increasing queries of timthumb issues, i plan to add an option of using wordpress core resizing for thumnails as an alternative to timthumb.