Locks are an essential part of everyday life. They protect you and your family, as well as your belongings. Whether you need a lock changed or you've locked yourself out of your home, a residential locksmith has the tools, knowledge, and credentials to help. Here are three things you can do when you run into problems with a residential lock: 1. Bring the lock to a locksmith. If you want the fastest service possible, you can do a little of the work yourself.