Answer:
To unravel me you need a simple key, no key that was made by locksmith's hand. But a key that only I will understand.
Neither bought nor sold but more valuable than gold. It is built but not by hand. What is it?
Put into a pit, locked beneath a grate, guarded through the night, yet it still goes out.
Three little letters. A paradox to some. The worse that it is, the better it becomes.
What goes around the world and stays in a corner?
What did the piece of wood say when he saw the screwdriver and screws approaching?