I have music that I know is on my Nano, but there is no listing for the artist. The album titles show up, but not the artist names in the artist list. They were listed under artist name on my Nano previously, and now they're gone. My photos seem to be gone, too.
I have not deleted anything from iTunes, and when I connect my nano, in itunes, it shows these "missing" artists as being on my ipod.
I figured the problem out. What happened was, the two missing artist names were filed under compilations, for some reason. I highlighted the entire album in itunes & turned the "part of a compilation" option to "no."
Also, if anyone else has this problem, it might help to go into "settings" on your ipod, and make sure the compilations option is switched to off.
I still never figured out why my photos disappeared and then reappeared.