Finally, if the key refuses to wiggle free, you can try using ice to remove a broken key. The cold temperature of the ice makes the metal contract, allowing it to slide more easily from the lock.
Wrap a piece of ice in a paper towel, to prevent drips, and press it to the head of the key. Hold it down and wait for a few minutes. Then, attempt to remove the broken key again by jiggling it slightly, if necessary.