Wordpress featured images and media library thumbnail no longer displays

I have a WordPress blog that is on a VPS. Everything has been working fine until today when I realised that my featured images are no longer displaying. I logged in to my dashboard, media library, and all the image thumbnails are no longer displaying properly.

Before this time, I had a little issue with my caching plugin (W3Total Cache), so I deactivated it, and my site continued to function normally. But now, no featured image is displayed all through the site. What amazes me is that inline images in a post are still displaying in the site. See example.

Now my site's homepage is just blank, because no featured images are displayed. As of today, images which I attached in the post are just seen as links, but if the link is clicked, it redirects to the image. Here are some of the things I've tried so far:

I've run df -h ssh command to verify if my diskpace is full.
I've restarted mysql server several times.
I've manually downloaded wordpress .zip file, and upload to the site.
I've automatically reinstall wordpress using http://www.example.com/wp-admin/update-core.php.
I've switched to a default theme.
I've tried some of the resources similar to this question here, but none of the proffered solutions resolved my issue.
My permission settings for all the sub-directories under wp-content is 755. I have also tried changing them to 775 and 777. *. I've used the Regenerate Thumbnails plugin to try to regenerate the thumbnails, but it returned an error The error message was: The originally uploaded image file cannot be found at, but when I view the image directly from my browser, it returns the image.
I've also used the WP Original Media Path plugin to try and restore the media path (if it was messed up), but to no avail.
I've deactivated all plugins too.
I just checked my wp_postmeta table in my DB and it returned this error wp_postmeta table is marked as crashed

How do I rectify this issue?

Solution

Since the source of your homepage has nothing in the main section:

<section class="entry-content clearfix" itemprop="articleBody">
                                            </section> <!-- end article section -->

and also due to the last item in your question, I assume you have a database problem instead of missing files (which I think would throw some 404s in my browser instead).

Do you have WP_DEBUG_LOG? If so, check wp-content/debug.log for errors. Be sure to launch phpMyAdmin and browse around the tables to see everything is good in there.

Use CHECK TABLE to confirm if tables are corrupted, and in that case use REPAIR TABLE to try to fix them (maybe phpMyAdmin has those in its GUI, I'm not sure right now).