
If you are locked out right now, your first priority is getting back inside. Try your building super or doorman first -- they may have a spare or master key. If they are unavailable, call a licensed locksmith for emergency entry. A professional can get you inside without damaging your lock, typically within 15 to 30 minutes.
Do not try to force entry yourself. Kicking in a door or prying it open will damage the door frame and possibly the lock, leading to much higher repair costs than a locksmith call.
Once you are inside, think about where the lost keys might be. If there is any chance they were lost near your building, in your building's lobby, or with any identifying information attached (like a name tag or address), you need to act quickly. Someone who finds your keys along with your address has the ability to walk right in.
If you cannot account for where the keys were lost, rekeying your locks should be an immediate priority. Rekeying changes the internal pins so the lost keys will no longer open your door, while keeping your existing hardware in place. This typically costs $50 to $150 per lock -- much less than worrying about unauthorized access for weeks.
If your locks are relatively new and in good condition, rekeying is the faster and more affordable option. If your locks are old, worn, or you have been meaning to upgrade your security anyway, this is a natural time to install better hardware.

In most NYC rentals, you are required to notify your landlord or management company if you change or rekey the locks. You must also provide the landlord with a copy of any new key. This is a legal requirement under New York law. Failure to provide a key can be grounds for a lease violation.
If you live in a co-op or condo, notify your building management and update any key records they maintain. Many NYC buildings keep emergency key copies for maintenance access and fire department Knox box systems.
Lost your apartment keys? Our locksmiths can rekey or replace your locks the same day to restore security.
If there is any chance the lost keys could be connected to your address -- for example, they were lost near your building, had a tag with your info, or you cannot account for where they are -- rekeying is a smart precaution. If you lost them far from home with no identifying information attached, the risk is lower, but rekeying still provides peace of mind.
If you lose your keys and request the landlord to rekey, they can typically charge you for the service. If you hire your own locksmith, you pay that cost directly. Either way, you must provide the landlord with a copy of the new key.
The found keys will no longer work in the rekeyed locks. Keep them as spares for any other locks they might fit (storage, mailbox, etc.) or dispose of them. The cost of rekeying is the cost of security -- better safe than compromised.