You need needle-nose pliers or scissors with very thin tips. Lubricate the area around the key, then grab the end of the key that comes out of the lock with pliers or scissors.
Try to pull the key out, being very careful. Do this little by little, without pulling forcefully: you run the risk of pushing the key further into the lock.
If the key has broken in the lock, but the door is still open, you can try one of the following tricks.
First trick
If the key is stuck with the door open, look for keys with a very thin tip and from the opposite side (i.e. inside the house) insert one of the tips of the scissors until it comes into contact with the key.
Push inward to help the key come out completely. If you can’t get it all out, you can use pliers to extract them completely.
Second trick
