Inspired by Bach's Well-Tempered Clavier, Chopin wrote a set of 24 preludes for piano each in a different major or minor key. The No. 20 Prelude in C minor is sometimes called the Chord Prelude because it consists mostly of a sequence of chords, with a characteristic descending pattern in the bass. There is a lot of modern-sounding chromaticism (and drama) in this progression of chords, and perhaps that's why these have been borrowed by composers including the song-writer Barry Manilow in his song "Could It Be Magic". You can download this prelude as PDF format sheet music, or as a midi or mp3 file using the links on the left-hand menu. The video below allows you to see the sheet music being played in Sibelius, and below that you can play the mp3 file and see the sheet music before downloading.
Here is a video of Chopin's Prelude Op.28 No.20 for piano:
The audio controls below allow you to play the mp3 version of Chopin's Prelude Op.28 No.20 for piano or you can download the MP3 file. You can also download the midi version of Chopin's Prelude Op.28 No.20 for piano.
The image below is the first page of the sheet music, and here you can download the full sheet music for Chopin's Prelude Op.28 No.20 for piano in PDF format.