I know this doesn't help with this situation but if you're making major changes and saving often it may help in the future.  Always affix a number to the name of the picture.  When you've just finished making a change and saving change the number from xxx.01 to xxx.02 etc and save a second time under the new name BEFORE you make the next change.  That way if you hit save rather than save as once a change has been made you're saving to a new file anyways.  If you hit save instead of save as while you should be making the new file, no change has as yet been made so you're just resaving the same picture version.