What is the make, model & year of your car? Some cars you can program the new key yourself. And some of those keys are under $30.
Selling dealer knows the code.
You can drill out the old one.
You can get a lock smith to show you the best course for whatever it is.
There are so many. that has to be your best advice.
Unless you want to go ask questions at the locksmith to bring him the keycode, HE has to get it.
Knowing what kind it was and what year is where you start getting your info.
like any automotive question.
in the meantime get the mystery machine and retrace your steps till you find where it fell off your ring.
in a chair? on the floor? in a car you rode in?
in your couch, they eat things. etc.
Someone turned it in to the lost and found?
Go down your phone list and retrace yourself and search.
See if the cars books and literature had the identifier for the keycode because your car is too old to be kept by the dealer.
Use your spare. Only stupid people own a car with only 1 key.
poor thing.
