You didn't tell what "everything" is, so I assume you already did it the way it has to be done: in Windows Explorer browse to that folder and from the menu choose View>Thumbnails.
It's possible the thumbs.db file in that folder (might be a hidden file, or even a hidden operating system file) is corrupted. Just delete it then and it will be rebuild.
If it's in all folders all over the system for all Windows users (also try a new one that you create in Control Panel), and this doesn't help, it's another problem. If you really tried "everything" and it didn't help, it can't be done. Except possibly by a system restore back to when it worked, but even that is doubtful.
Kees
How do I change the way my pictures show in my files? They use to always be thumbnails but now they show as lists. I've tried everything and they keep going back to lists. I have IE8, Windows XP SP3. Thank you!

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic