Lock Smith / Dealer.. Or a Junk Yard.
Buy a new 2000 ford expedition
Buy a can of lock unfreeze or wd-40
Radio Installer Shop or www.crutchfield.com
Buy a repair manual like Chilton's they have wiring and vacuum diagrams.
About the only way I know is to find one in a wrecking yard.
i think you should buy special tools for it or ask a mechanic.
Go to NAPA and buy a repair manual for your specific car.
Buy a 2000 Ford Lightning super charger, fuel pump, etc. Install it. That's only if you have the 5.4.
To buy accoutrements for the expedition
You can buy new locks and replace them in the door they cost about 15 dollars a set if you do it your self but you can pull the door panel inside off and chect to see if the rod that connects to the lock is still connected.
An expedition that you go on for a commercial reason, like to buy something or make make money.
One can buy a folder lock from the provider "New Softwares". This folder lock also has a free trial period if one wishes to try before one buys. The programs name is "Folder Lock 7"