Welcome to the Apple Discussions. Move the Themes folder to the Desktop and reboot. Then move it into the HD/Library/Application Support/iPhoto folder, repair disk permissions and reboot again. Then launch iPhoto and see if you can print. If not there's nothing you can do until you reinstall iPhoto.
What application are you using to print with now? Can you set it as the editor or choice in iPhoto's General preferences and then reset the preferences to use iPhoto for the editing.
If you can do that then edit the photo with iPhoto. When that's completed Control-click on the photo and select Edit in External Editor. That will open the photo in the application you chose so you can print from it. Preview will work nicely if it prints as you want it.
OT