How do I replace the lock on the driver's door?

If you are handy wheatman the most economical course of action is to switch the driver's side lock core with the passenger side lock core. Chances are that the passenger side lock is rarely if ever used. If you don't feel that handy getting the job done at a dealer will probably run you about $200. They will special order you a lock cylinder which will require a different key code than your ignition key but they will code keys that will work in both locks so that you only need one key ... Good luck!

It could also be as simple as the rod that is connected to the lock has come off, there is a small clip holding it on. You have to remove the door panel and probably peel back the plastic water seal to get to the hole near the lock. It is probably a tight fit but you should be able to look in and see the rod or squeeze your hand or fingers in to feel for it. Be sure to put the plastic back in place or tape back over the hole or you will get water leakage.

I realize this is very, very late. I had the same problem and it turned out to be that my key was too worn out. It still worked in the ignition and the trunk, and the passenger side door. I thought it was the driver side door lock given how much it was used, but it took my seeing a fracture on the key itself that made me pull out the last master key I had and when used, all was good. Also - call a licensed locksmith for making a new car key and expect a quote of nearly $100. If you go to a dealership, it should be a lot less. Bring your id and registration and so long it all matches they'll do the job. If your addresses don't match then bring your pink slip just in case to prove ownership.