I have accidentally deleted over 6,000 of my favorite pictures from my Mac (IPhoto), ALTHOUGH, I still have the thumbnails. Is there any way to recover full size pictures from thumbnails? This would be a life saving answer.
When you delete some files from the software they are moved to Trash by default. You could try and see if the files are in that location but there is a big possibility that the files were long deleted which in this case there is another solution: using TimeMachine to restore your computer to a previously state in the past or simply start the application and navigate to where the folders were stored in the past. Also notice that if you copied additional content on the hard drive, it is most likely that the new content was written over the old one thus making the recovery impossible.