Recommend a locksmith?

AAAAAAAA Locksmith

For fancier locks like Medeco, take the cylinder out (using a screwdriver) and bring it to Home Depot (call first to make sure the right employee will be there when you arrive) ... ask them to rekey it. $10 or so. Replace the cylinder.

For a humdrum ordinary lock, buy a new cylinder for something like $5 ... you can figure out how to swap it out yourself with just a screwdriver.

I like the 1970s look, with about 15 different locks, chains, jimmy bars and police locks running up and down the side of the door.

And a high-distortion peephole. Girls Girls Girls. Live Girls.

You're getting me all nostalgic for the police locks on my old tenement doors, and carrying three or four house keys around. I'd always thought they were called Fox locks, but just now got the right name from google.

This apartment has only the one mortise lock, but the bolt holes and chipped paint from a couple of Yale locks and a chain.

I highly recommend Jay from lockbusters.
http://www.lockbustersnyc.com/

I'm normally a fiend about carefully looking for and researching good workmen, but I have to say that in my experience any random nearby locksmith can change locks. On one apartment someone even told me how to cheaply change the Medeco cylinder myself and, now that I think of it, once I didn't even bother changing the locks. I figured that any danger was going to come from a burglar, not the previous resident.