Walt, this link doesn't include the lead melody notes, but does include the chords & lyrics: http://www.guntheranderson.com/v/data/maria.htm

Once you have the melody in your head (perhaps after listening to it on a cd/record,mp3, or midi file), I would expect you should then be able to play it (by ear) on the keyboard with the help of the given chords as a guide.

Scott