My Edits are there, but 'Revert to Original' has gone

Question

Sorry, yet another iPhoto problem
I've noticed that though all my recent iPhoto edits are still there, the 'Revert to Original' has gone, for all of them. And the sliders - which should be in their post-edit positions - are all at zero or default.
I tested this by duplicating a recent edit, editing it dramatically (full saturation and colour temperature), came out of Edit, and went back in - no clickable Revert, and all sliders back in their default positions. I checked in the menu, and Revert to Original was greyed out.
I then went into Edit mode and flicked back through the Library. Occasionally the Revert to Original button was clickable, but as far as I can remember, those were all edits done ages ago in a previous version of iPhoto (and maybe not all of them?).
I thought iPhoto '11 kept track of editing adjustments, i.e. it was non-destructible editing? I appear to have a version that saves and preserves the edit(s), but overwrites the original.

Answer 1

Starting over from scratch with new library
Start over with a new library and import the Originals (iPhoto 09 and earlier) or the Masters (iPhoto 11) folder from your original library as follows:
1. Open the library package like this.
https://discussions.apple.com/servlet/JiveServlet/downloadImage/2-20276325-17180 0/open.PNG
2. Launch iPhoto with the Option key held down and, when asked, select the option to create a new library.
3. Drag the subfolders of the Originals (iPhoto 09 and earlier) or the Masters (iPhoto 11) folder from the open iPhoto Library package into the open iPhoto window a few at a time.
https://discussions.apple.com/servlet/JiveServlet/downloadImage/2-20276325-17180 2/iPhotolibcontents.PNG
This will create a new library with the same Events (but not necessarily the same Event names) as the original library but will not keep the metadata, albums, books slideshows and other projects.
Note:  your current library will be left untouched for further attempts at a fix if so desired.
Sorry, I got your email but your reply hasn't appeared in the Discussions (NOW it has! just when I post the reply..), so I've pasted it here (hope you didn't mind).
Anyway, since then, when everything else failed, I did already have a look inside the Package, and there I saw all my Original and Modified versions, so I knew they were still there. It's just a case of why iPhoto isn't offering to Revert to them.
Ok, I have some questions about your latest advice (which is going to be a BIG JOB!!).
When you say Metadata, do you mean I will lose all the camera's EXIF data (that normally shows if you click Info)?
What about Ratings? One of the big exercises I'm currently currently halfway through - 4,500 photos! - is rating them all - will I lose all the ratings?
When you say drag Originals / Masters to the new Library, what about Modified? Remember, I can see all my edits - they are in the Library, it's just that I can't Revert to Original in many cases. If I don't drag the Modifieds over, won't I lose all my edits? (I'd rather lose the Originals!)
When you say drag the subfolders, they are nested several deep, e.g. 2013 > 09 > 20 > 20130920-193215 > (a bunch of picture files). Do I have to recreate the directory structure, or could I just drag 2013 > 09 in one go, with everything inside it? And would I have to create 2013 folder first, then drag all of 09 into that?
Sorry to fire so many questions at you - it's a big undertaking. (I might find in the long run, that if ever I want an Original back, I should just Open the Package and retrieve it manually, so it duplicates rather than Reverts. It's not something I do except once in a blue moon, so I might decide to live with the current situation... )
Anyway, let me know what you think : it's either undertake this major task, or live without being able to Revert To Original from within iPhoto itself.