How to Replace a Lost Key to a House Door

Lost your house key, huh? Don't worry; it happens to the best of us. Maybe you inadvertently used it to pay for coffee or perhaps you just put it somewhere and you'll remember where some morning as you're waking up.

As long as you can still get into your house, a lost key isn't a major problem. A locksmith can make a new one. It's important to remember, though, that someone may have found the key and could potentially use it to break into your house. So unless you know for sure that the key is irretrievably lost (it fell into a well or you dropped it off a bridge), it's safer to rekey or replace your lock.

Whether you have a locksmith make a new key for the existing lock, you rekey the lock, or you replace it altogether, you're going to have to remove the lock from the door. That isn't as difficult as it sounds no matter whether it's a deadbolt or a keyed handle set.

1. Locate the screws holding the lockset to the door. They are on the inside of the door and may be hidden by a cover plate. If so, pry off the cover plate using a flat-head screwdriver.
2. Remove the screws using a Phillips screwdriver and pull the two halves of the lock apart. The keyed part, which is on the outside of the door, is the part you want. It should just fall into your hand after the screws are gone.
3. If your plan is to replace the lockset or handle set, unscrew the barrel strike from the side of the door and pull out the barrel mechanism. The replacement will likely require a different mechanism.

Once you have the keyed part of the lock in your hand, you can take it to a locksmith, who will be able to make a new key. If you're concerned that someone might have found the key you lost, however, it's better to replace the lockset or rekey it.

You can have a locksmith rekey your lockset, but it's also a job you can do yourself. To do it, you'll need a rekeying kit that works with your brand of lockset. Most major manufacturers, including Schlage, Kwikset, and Defiant, supply them. You can find a kit at your local building center or online. You can buy kits that work for multiple brands, but they are more expensive than a new lockset, so if those are the only ones you can find, it makes more sense to go to a locksmith or replace the lockset.

Follow the instructions that come with the kit to rekey your lock. The procedure involves removing the pin cylinder using the tools provided in the kit, dumping out the old pins and replacing them with the ones required for the new key, and reinstalling the pin cylinder. The kit usually comes with two new keys, so this time, put one in a safe place in case you lose the other one.

The worst scenario of all is that you're locked out of your own house, and if you can't find an alternate entry, you may be tempted to pick or jimmy the lock to get back inside using paper clips or a credit card to push back the spring-loaded lock barrel. Unless you have lock-picking skills, though, this is usually a bad idea that probably won't work and can damage the lock or your valuable credit card.

Most locksmiths have 24-hour emergency service, and if there's one in your neighborhood, that's your best option for opening the door. Once you have access to your house, you can ask the locksmith to rekey or replace the lock, or you can rekey the lock yourself.