Folder contents (photographs) populating on top of each other and some cannot be accessed

What the heck is going on?

Suddenly I cannot access most folders on my hardrives. They populate on top of one another, except for the first line. I can put them in list order, but need them in thumbnails! The accessibility changes randomly, most files suddenly appearing with a dropshadow on them which means I cannot work with them. This is a mess! I am having trouble with Photoshop as well so I am doubly frustrated.

In the image below, you can see a drop shadow on images and a darker highlight on the folders. None of those images are able to be opened!

This is so frustrating! Can anyone assist?