A complete and official Zelda: Twilight Princess OST was unfortunately never released. However, some people were able to compile their own soundtrack using a few official tracks and tracks recorded directly from the game and have shared this compiled soundtrack with others. The following are such tracks.
Remember, if you like this music, support its creators as best you can by purchasing Zelda: Twilight Princess! This is an incredible game with beautiful music, and it belongs in every Zelda fan's collection.