Okay, I'm not sure what you're asking.
If you use PSE as external editor (or any external editor or if you make changes in iphoto itself) you no longer see the original. If you want to get back to that, the only way is to use the Revert command, which will bring back the original at the cost of losing the edits. It's one way iphoto is different from programs like Organizer.
Now if the question is where did you save the exported copies on edit, then you need to do a search for them to figure out where they went, because they go wherever you save them, so pay attention to the chosen location in the Save As window and be sure it's where you can easily find them again.