Q: 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.