iPhoto problem. Should I update to newer version?

When I open iPhoto (version 7.1) I do not get rows of thumbnails. I get one large picture. I can scan through the pictures. I can edit them. I cannot select or drag them. I do have small thumbnails across the top when in Edit mode. I have been scanning pictures a lot of photos onto the computer. I backed up 1 day before this problem occurred so I have a backup. Should I try to rebuild thumbnails (and how do I do that)? Should I try to restore Iphoto from the backup? Or should I try to update iPhoto with a newer version? What version should I get? I have OS X 10.6.8 Snow Leopard. Speed 2Ghz. Memory 4 GB.