You might think that this was an early work composed by the young Mozart, but it was actually composed later in the composer's short life as a simple work for young pianists. More piano sonatas and "fantasies" are available from Sheet Music Plus (US) or The Music Room (UK).
The audio controls below allow you to play the mp3 version of Mozart's Piano Sonata in C (1st movement) or you can download the MP3 file. You can also download the midi version of Mozart's Piano Sonata in C (1st movement) or alternatively edit/play the midi file.
The image below is the first page of the sheet music, and here you can download the full sheet music for Mozart's Piano Sonata in C (1st movement) in PDF format.