5 switches, 5 leds, 5 tones, in an Array
You have a rogue ; here:

  for (int i = 0; i &lt; sizeof (LED) / sizeof (LED[0]); i++);{
  pinMode(LED[], OUTPUT);                                 ^------HERE
}


That is terminating the for, making it empty, and the following block is a completely different scope.

Another thing I spotted - you aren't putting i into your array index LED[] (should be LED[i]).  The same is true with Buttons[].

However, on a different subject, this:

buttonState == digitalRead(Buttons[0]);
buttonState == digitalRead(Buttons[1]);
buttonState == digitalRead(Buttons[2]);
buttonState == digitalRead(Buttons[3]);
buttonState == digitalRead(Buttons[4]);


is pretty meaningless.  You are comparing values and throwing away the result.

In a similar vein:

if (buttonState = Buttons[0])


stores the current value of Buttons[0] into buttonState and succeeds if Buttons[0] is anything other than 0.  The same goes for all the others.

You need to sort out your comparisons (==) and your assignments (=) and also sort out what you think you are doing with all those buttonStates at the top of loop.