Sorry about the music, I'll try and fix that. The puzzle can only start when the note on the floor is picked up.
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Sorry about deleting my previous post but it was a bit redundant. I have tested the game again, and I have not found any problems on my end. As of right now I can think of two possible reasons why you are having problems, the first is that somehow you are not using the default controls. And the second is that your volume might be too low. For the first possibility, you'll need to hit F1 while running the game and reset the key bindings. The second possibility should be easy enough to fix.
EDIT: (edited the to my as to clear any confusion.)