Hi, did you also include the potentiometer? You can turn that in different directions, it will control the contrast of the display. I think that should fix your problem :)
I used a 220 ohm resistor on the lcd display (as recommended, I believe) and a 10 kilohm resistor on the switch button.
Good luck, hope it works!

You have to include the pitches.h file, then it should work. You can find it here: https://www.arduino.cc/en/Tutorial/toneMelody (The second set of code on that page).

I'm sorry, I'm not yet very good at programming for Arduino, I'm not sure what goes wrong. The code works for me. Maybe you have the same problem as below in the comments?