Product Gallery Gone???

A few weeks ago, I checked out the product pages of my website to discover that the product gallery images (the thumbnails located underneath the featured image that you click on to view more pictures of the product ) have ceased to appear, although they are selected and assigned to products from the admin panel. I tried deleted and re-uploading my entire media library, but the galleries still fail to appear on my product pages, leaving me with only the featured image viewable. I also tried to update to 3.8, but nothing seems to work. Please help!

Thanks,
Ryan