Not all security problems are attributed to locks. Sometimes, it's the key's fault. Sometimes, it's our own fault. We might put the wrong key in the wrong lock or apply too much pressure. Keys won't give us problems when they are in good condition and it's certainly our own responsibility to make sure they are not damaged and not used when rusty. At times, the might be unusable when the door locks are stiff or even frozen. Such problems will give us a headache since we won't have access to our property or won't be able to lock the door. So, it's good to know how to extract the key when it is stuck in the lock for whichever reason.
Different methods are followed for stuck and broken key extraction. It's not the same dealing with a broken key and dealing with a stuck one. Then again, the extent of the problem will vary depending on whether you can see the edge of the broken section and on whether the right or wrong key has been used. If the wrong one is inserted, it will be very hard to remove it. Although it is difficult to insert the incorrect key in a security lock, it's not impossible. It will depend on the pins of the cylinder and the force you used. As a matter of fact, by doing that you might have already caused damage to the mechanism. It would be better to have Locksmith Brentwood check the lock to see if there is need for lock replacement.
If the key is stuck, avoid using force or the pins as it may damage your lock further. If this happens, lock change will be unavoidable. You must be gentle and turn the key right and left in a smooth way. Some lubricants will help. Spray the lubricant on the keyhole and keep moving the key till it comes out. Things will be tougher in times the key is broken. It will also depend on whether you can see part of the broken section or not. If you cannot, you are basically out of luck and it would be easier to replace the whole deadlock. For your convenience and avoidance of drilling new holes in the door, get a similar lock of the same size.
If part of the broken section is seen, you should grab it with tweezers or pliers gently and try to remove it. Remember that the key must be in its original position (when it is first inserted in the keyhole) and not turned. Otherwise, it would be impossible for you to retrieve it. If it's turned, use the tool you are holding as it were the head of the broken key and turn it to the original position before trying to extract it. If you have a hard time getting it out, spray lubricants. In times of extreme conditions and when the key is not extracted easily due to the freezing weather, turn things around by changing the conditions. Use the hairdryer to warm up the lock and make the same soft movements till the key is out.