From your description, I guess the photo creation dialog box is opened but out of sight, even if normally this shouldn't happen. Or maybe, you have to monitors and the second one is turned off.
Anyway, you should be able to fix your sh3d file following these steps:
1. create a backup of your .sh3d file
2. change its extension to .zip
3. edit the file [font=courier new]Home.xml[/font] in the .zip file to remove the lines containing the text
property name='com.eteks.sweethome3d.swing.PhotoPanel
4. save [font=courier new]Home.xml[/font] and the .zip file that contains it
5. change its extension back to .sh3d