Ron,
Perhaps you already have an answer... I'm assuming you're running a recent version of Windows, and I'm reading between the lines a bit; it sounds like you changed your view style into a list. To change it back, navigate to the directory in which you have your pictures. Select "View" on the top line menu, the menu line that starts with "File." Then in the Layout selection box, select one of the icons options, such as "Large icons." That should get you back to seeing thumbnails in your listing.