When playing a song, it only plays 30 seconds of the track. Why?
We really need more details to answer this question. If you're talking about something like iTunes or Amazon, you're effectively listening to a 30-second preview of each song, the idea being it encourages you to buy the full song. If you want to listen to full songs for free then try a dedicated streaming services such as Spotify or Rdio.
is it on external hard drive? if yes perhaps something to do with drive letter
perhaps you are trying from XBox music database
are they itunes purchase perhaps are DRM protected
also which version of Windows you have
Richards, can you clarify:
1. What kind of tracks are these? Downloaded tracks from the internet? Things you recorded/ripped yourself? Material streamed from a web site (which?)?
2. What software are you using to play the tracks? Also, what version of Windows are you on (Vista, 7, 8, 8.1)?