How to rekey a lock
If you have many locks in your home or just want to simplify the process by not actually changing your lock, then rekeying a lock is the easiest solution. You will need to remove the lock mechanism from the door, which is always different than installing the lock on a door. To remove the lock mechanism, there is typically a bolt or two that holds the lock in place on the inside of your door.
Once these bolts are removed, the lock mechanism can slide out very easily. At this point, you have two options. The first is to take the lock with the original key to a locksmith and have them do it at their place of business. This reduces the cost of a house call, which is very expensive! They can reconfigure new pins that will work with a brand new key that is made at the same time. This is the cheapest solution and often doesn't cost more than $5-10 per lock.
You can try ordering a do-it-yourself kit from online sellers at Amazon that will be around $12-25 per kit, but you can also look for these kits at a hardware store. Some decent how-to videos on Youtube show you how to reset the pins for a new key if you want to rekey a lock yourself. But to make sure that the lock is rekeyed properly, you should call a professional locksmith.
New York City, NY