If you have the new p168C like myself, you'll find the way to organise your music player is a bit different.
You'll notice there are two folders for your audio files; Audio & My Music.
Place all the files you want to play through your audio player into the 'My Music' folder, and all the audio files you don't want to play through your audio player playlist into the 'Audio' folder (such as sound clips and little ringtones).
Once you have made any changes to the my music folder (added files, deleted files, renamed files etc.)
go to 'menu(or home key)'>'multimedia'>'audio player'>'list'>'options'>'refresh list' to update the audio player to correspond to the changes made to the files.
any questions just ask