Answer:
I can be cracked, made, told, and played. What am I?
I am a rock group with four members all of whom died in plane crashes. Who am I?
What body part is pronounced as one letter, but written with three, only two different letters are used?
Walk on the living, they don’t even mumble. Walk on the dead, they mutter and grumble. What are they?
I have no voice but I can teach you all there is to know. I have spines and hinges but I am not a door. Once I've told you all, I cannot tell you more. What am I?
The answer I give is yes, but what I mean is no. What was the question?