First, go to View > Pictures and check that 'Hide pictures' isn't selected. If it is, the solution should be obvious. If it isn't try selecting 'Hide Pictures', closing Publisher, re-opening it and selecting 'Detailed display'.
If that doesn't work, go into the Graphics Manager. (It's accessed via Tools > Commercial Printing Tools and see if anything here makes sense:
http://en.allexperts.com/q/Microsoft-Publisher -1036/Publisher-photos-1.htm
If that doesn't work, reinstall Microsoft Publisher. (From memory, I think that installing without uninstalling first will offer you a 'repair' option, which might do the trick).
Chris