http://imageshack.us/photo/my-images/201/awrf.jpg/
As you can see, it ignored 218,529 files after a deepscan was completed.
Is it possible that not even a single file is recoverable.
You should see results if you ☑ tick all three . . 
You will see even more if you check the Scan for Non-Deleted Files box. You do not have to rescan after checking/unchecking these boxes. Recuva v1.44 includes non-deleted files in its default scan, but does not show the results unless the correct box is checked (which is why there is a large number of ignored files).
This brings us to why there are no deleted files shown. After checking K's boxes you may well see some results, but these won't be useful files, which is why the default for these boxes is unchecked. It is very hard to believe that you have a completely clean disk, but at the moment I am clean(|) out of reasonable theories.