Successfully lock or unlock your door
One of the easiest ways to find that a door lock is broken is that it can no longer be operated by specifying a key. Basically, if the specified key cannot unlock your door, it is likely that there is a problem with your door lock cylinder. I will play the Devil's Advocate for just a second and say that you may have a broken key that is equally reasonable, but it is easier to find than the door lock damage. Make sure you take the time to check your keys correctly so that you can exclude them as the culprit and focus on the door locks. If the key can rotate the lock but does not successfully lock or unlock your door, it may be a sign that your door lock is broken.
If the key does not rotate in the lock at all, it indicates that your lock may be damaged, which is a clear sign. This is a very different situation from the above, which may be a clearer indication that the internal mechanism of the lock is not working properly. If the homeowner notices this, they should make sure they take the appropriate steps to repair their door locks.
If the key is stuck in the lock, or if the operation becomes more and more difficult, then the designated key is used for locking. You will notice that the fluid action once the key is inserted into the lock and unlocks the door no longer exists. It is also increasingly difficult to remove the key from the lock. Note that these marks will help you repair the damage and become more serious before the lock propagates. It can also help you prevent damage to any other components used with the door lock.
There is no hidden science to help you figure out if the door lock is broken, but there are some things you can do to help you diagnose the problem effectively. The ability to identify your door locks from being destroyed will help you correct the problem and it will reduce the possibility of causing more damage.