Destrabar cerradura mis 2 métodos para solucionar en los casos más comunes.

The half that needs to be cut off is the part that interferes with the lock mechanism when the key is turned. When you insert the key, the lock mechanism, usually located at the top of a standard lock, is the part that interferes with the mechanism. This is the half that needs to be cut off to prevent it from turning. If you accidentally cut off the wrong part, you can use it on the other side of the door. If you're unsure, try forcing it in upside down without cutting it. Good luck. I recommend keeping the modified key in case it happens again; you'll have a backup. Check that the lock doesn't rub against the door frame when opening and closing, meaning it shouldn't scrape against anything, and that the screws on the lock itself (the one you disassemble to see the mechanism) are properly tightened. If the mechanism is heavy when opening and closing, open it and clean it with a small brush using kerosene, gasoline, or diesel, leaving it clean inside. If you want, you can apply a light oil like WD40 (not machine oil) because machine or heavy oil collects dirt and clogs up, and don't even think about using grease.