This prelude is from Johann Sebastian Bach's The Well Tempered Clavier, or The 48 Preludes and Fugues. The prelude should ideally be played at a slow pace, with the quavers forming a steady tempo. Bach's Preludes and Fugues come in matched pairs in the same key, and are often (though not always) played as a pair in the order Prelude first and then Fugure. Here is the corresponding Fugue for this Prelude, also in the key of B minor. This prelude and fugue are the final pair in book1 of the WTC and catalogued as BWV 869.
Although there are some easier preludes and fugues in the set, much of Bach's Well-Tempered Clavier is quite challenging to play. However the complete set has for a long time been considered a must for any serious student of piano. Some other preludes and fugues from the set are available on mfiles if you check the Bach page or Classical Sheet Music page. If you have aspirations to be a good classical pianist then we recommend getting the complete Well-Tempered Clavier which comes in two books. Here are links on "sheet music plus" to Book 1 and Book 2 of the Well-Tempered Clavier.
Here is a video of Bach's Prelude No.24 from book 1 as a piano roll animation:
The audio controls below allow you to play the mp3 version of Bach's Prelude no.24 in B minor from Book 1 or you can download the MP3 file. You can also download the midi version of Bach's Prelude no.24 in B minor from Book 1.
The image below is the first page of the sheet music, and here you can download the full sheet music for Bach's Prelude No.24 from book 1 in PDF format.