I did about an hour's work on a Smart Object (an image I had placed in a file). I saved the smart image and closed it, but the changes did not appear on the original. I opened the Smart Object again, and it opened without any of the changes I had just made.
Some further research seems to suggest that this is because the original file was a .jpg, so when I saved my modified the file and saved it as a psd all my changes were lost, since Photoshop only checks the original .jpg for changes.
Is there a way of recovering my work? What is the location of the Temporary Items directory?