Regardless of whether the lock was stiff, you used the wrong key or Murphy's Law struck once again, a key breaking off in a lock can be a frustrating experience. After trying desperately to pluck free the portion of the key stuck in the lock, many resort to enlisting the help of a professional. Unfortunately, locksmiths are typically very costly, but you might be able to avoid the expense by implementing a bit of ingenuity.
Spray lock lubricant or all-purpose lubricant into the key hole and wait a few moments for the lubricant to take effect.
Slide the jigsaw blade or pumpkin carving tool into the lock alongside the key.
Manoeuvre the jigsaw blade or carving tool to move the lock from the locked position to the neutral position. The slot into which the key is inserted should be vertical when in neutral position.
Gently wiggle the serrated edge of the blade against the key until it catches the groove of the key.
Pull the blade or carving tool outward, while holding it tightly into the groove until the key begins to protrude from the lock.
Grasp the protruding portion of the key with the needle-nosed pliers or tweezers and pull the key the rest of the way out of the lock.
If your attempt to remove the broken key from the lock yourself has not been successful, the pricey alternative is a house call from a locksmith. Another option is to remove the entire lock with a Phillips head screwdriver and take it to the locksmith or to a local hardware store where a professional can then remove the key at little or no cost. Copies of keys can often be made by providing both halves of the broken key.