What if someone has changed your lock with their rekey kit?

You have to have the original key to re-key.

you need a working key to start the process

To rekey a Kwikset Smartkey lock, you must use the current working key in order to rekey the cylinder to a new one. Without having the current working key, the lock cannot be rekeyed. Lowes stores carry a tool called a Reset Cradle that can fix that issue for you and rekey it back to your original key. Please check with your local store to see if they offer this service before driving out to the store.

If someone re-keyed your lock, they had to have the working key in order to do it. To get it re-keyed to your key, take the lock and key to your local Lowe's and the hardware associate should be able to reset the lock to your key. I would suggest that you buy the reset kit and have the associate reset your lock to the new key. The reset kit will not reset your lock without the working key. Hope this helps.

No. You will need a key that works the lock to change it back.