Looking through my gallery I notice that some of the thumbnails appear blank (black). When I open a folder with some of these in I am able to scroll through the pictures, but when I come to one of these blanks (where there used to be a picture) nothing opens - just a blank screen. I can, however, continue to scroll on to the next which will be displayed correctly. Also I am unable to delete such a picture. When I tap on it I get the option to delete, which I select, but it just says "loading file" but it fails. I am still able to scroll on to the next though. So, my question is how can I recover or (preferably) delete these blanks?