Sometimes keys break inside the key-way. The broken piece of metal can be very difficult to remove. In the meantime you can’t get a key inside to unlock the door. Sometimes a person has another key and another door they can enter through. In most cases though, the person has two problems: 1) They have a broken key stuck in their door knob 2) they are locked out. A locksmith can use specialized tools called broken key extractors. They can use these tools to remove the broken part of the key. They can then pick the lock in order to allow the person inside their home or business. If no other key is available they can make several keys on the spot that match the current doors.
If you find yourself in this situation we’d be more than happy to help you out. If you decide to call another company just be weary of anyone that quotes $35. This is a common bait and switch tactic. They show up, then drill the lock, charging significantly more.
In order to prevent his we recommend never using the key as a handle. Use the key to unlock the door, then turn the handle. Keys typically break from repeated stress of people using them as handles.