This is why you call a locksmith over a handy man, we can replace your locks but its cheaper to rekey your locks. The difference is when you rekey a lock we use your lock that is on the door but we change the tumblers in the barrel to a new key so the old key does not work.. One key? most times when we rekey a home we hand the owner one key that fits all the locks that includes security screens as well as all other door including the shed door… Give us a call and we will see what we can do for you..