Have you double checked the pathing of the sound folder and ensured all sound files are there? The "Cards" folder and "Sounds" folders need to be in the same folder as the application or the same folder as the source code. to work.
You can also download Blackjack Game File. zip for the .exe version of the game.
As a last resort, you can attempt to change the source code to not require music
EDIT: I uploaded a browser version so you can also try using that!!