Thank you both. I tried the little tool that was on the link that Baldur supplied, and it showed literally thousands of deleted files. For some reason the ones I wanted weren't all there, about 3 out of 30 or so. Anyway it was a help, and thank you.
There is a little background to this. I installed Picasa (for photos) the other day, and it copied every single image on my computer, including some I didn't even know were there (scary!!) and when I deleted the ones I didn't want, it seems to have deleted the whole folder that they were in.
Anyway not the end of the world.