Have testdisk and photorec or similar command-line tools been ported to the N9 yet? I don't personally know how to use them but 'photorec' is supposed to be able to recognize 'deleted' data in a storage medium, so long as no other data has gotten written over that same spot before, and common file formats like those used in music/videos/photos should be supported by photorec. So I'd say check if something like photorec is available on the N9, and if so, that might work for recovering at least some of the lost media.