Right click your music (in ubuntu) and tell me what it says on the audio tag. If has a bunch of unknown info (album,artist, year,) Fill it in with a program like Audio tag tool (look for it in add or remove). Have you added any music in mtp mode? if you have try
sudo apt-get install mtpfs
in a terminal. If you don’t have extra repositories enabled this wont work.
after you install that switch your player to mtp mode and plug it in. It should appear on you desktop as a I-pod. If it works. Try adding some music to it, eject it and unplug it. Now see if the music plays. Didn’t work? Then put it in autodetect mode and plug it in and try to add some music. If THAT doesn’t work then put it in MSC mode again and try it. If none of that works. Backup your music. Format your player (You can do this in the on the player.) Plug it in msc mode and add some FRESH music that you know is tagged properly and works.
FYI: Stick to one mode (msc,mtp,auto detect) I’d use msc if i were you. Oh and one last thing. Does your music have DRM in it?