The Prisoner!

Riddle: A prisoner was stuck in a metal room with a metal door that was locked. There was no windows and nothing in the room but a piano. What can he do to escape?

Answer: Play the piano till he finds the right key. Source: https://riddles.com/4928

A prisoner was stuck in a metal room with a metal door that was locked. There was no windows and nothing in the room but a piano. What can he do to escape? — The Prisoner! by Natalie Riddle