Its hard to say how this happened but my key broke off in the lock when I was opening the door. Maybe I don’t know my own strength or maybe the wear and tear of the key finally gave in but I couldn’t even get into my house with a spare key. This was serious dilemma. I called the locksmith and told them that I can’t get into my home. After that they got me stronger locks and keys that wouldn’t give in after a few years of use. These were some serious locks. You could take a hammer to these things and just bank away. Not that I would but I could.