Have you ever gone out and used your key on a lock that might be a little sticky and the key has broken off? This can be a terrible feeling since the part of the key that is stuck can allow the lock to be engaged and disengaged. That means that you cannot secure the lock or the entry point in any way. That is usually an emergency situation that you need to call a locksmith to come out and take care of the key removal. There are some ways that you can try to remove the key yourself but calling a locksmith is the best bet. The first step to trying to remove a broken off key is to NOT use the rest of the key at all. The more you use the extra part of the key the further the broken off part will go in and that makes it harder to remove in any way. Start the broken key removal by adding some kind of lubricant to allow the metal piece to slide out easier.

Best Locksmith lists of a few ways to remove a broken key from a lock cylinder.

Try to Use a Pair of Tweezers to Get the Broken Key out of the Lock: Any pair of tweezers can be used to remove the broken bit of key. Depending on the size of the key hole will determine if the tweezers will work at all. If the tweezers are too thick they may not be able to insert enough in to remove the key. You also can use this method if you have the broken bit of key out a little bit and can easily grab hold of it.
Use A Broken Key Extractor Tool: There is a tool that you can use to extract a key that has broken off. They key extractor is used most often by a professional locksmith but if you have this tool you are attaching the key extractor along the key teeth. You may need to try several times to get a hold of the key and remove the bit that has been broken off. Having some experience in using the tool is better when trying to use it and that is why most of the time a locksmith is the person best suited to this task.
Tap the Lock: This is an option that you can use if you are able to remove the lock piece. You can take the lock off of the door or drawer etc and set it on end so that the keyhole piece is facing down. There are some times that the key will just fall right out of lock and clear it for you.

If you have a key that has broken off in a lock, call Best Locksmiths in Racine, Oak Creek, Burlington & Kenosha Wisconsin.