I've read all the solutions given in this forum and changed
Organize > Folder and Search Options: View Tab from the default of the option "Always show icons, never thumbnails" from checked to unchecked.
I did a disk cleanup, checking only the thumbnails checkbox. Nothing works. The icons to the left of the file names are folders for folders and a generic picture of a mountain for every
jpeg. I used to see small images of the actual pictures, both at one time on this system and also when I had Windows XP. I'm at loss what else to try.