Where is the mechanism to unlock driver door on a 2003 buick rendevous

Most lock out companies use a long metal rod that is inserted through the top of the door and is then used to push the power door lock button or the lock button. If you gently pull on the top of the door and insert a wedge to keep the door ajar slightly, you can use a coat hanger and manoevere it to touch the door lock button

I'd ask your friendly policeman, or a locksmith.

Slim jim won't reach it because of how it has to be curved to get to the latch. You have to pry out the top of the jam/window. Then reach down with a close hanger to unlock the door. Don't push against the top as it will bend. Pull the window/frame out. It will bow out some. Put your knee in the middle of the door and pull the window/frame back into place.

Not to my knowledge. The mechanism you talk about is the wiring inside the door if it has electric locks. The only way is to remove the top of the door panel to access the door latch mechanism then slide it away from the latch. If that don't work let me know

You cannot as their are shrouds around the locks ,try winding a back window down if its a manual winder

You will need two plastic wedges and a piece of stiff wire (wire coat hangars work remarkably well) or a slim jim.
Insert the wedges between the metal portion of the driver door and the window to allow easier access for the slim jim/wire.
Slide it to the location of the lock bar. Hook the lock bar and yank to the right. This should actuate the locking lever and unlock the door.

take a slim jim or a coat hanger and unlock the door by sliding it down through the outside between the door and glass and pulling the lock mechanism up or take the vin code off the through the windshield are on the dash and go to a local lock smith or dealership and have a extra entry key made

Sorry to hear that your door is stuck closed. The problem is that the plastic clip that holds the unlatch rod into the unlock mechanism broke and the rod fell out. Since the door is closed, you cannot remove the inside panel, so you will have to open the door the way an auto locksmith would (with a slim-Jim tool that slides down the outside of the window into the door from the outside). You can buy one at some better auto parts stores or sometimes even from the larger 99 cent stores. My local 99 cent store has them. I recommend putting a small wedge into the door between the glass and the opening and slide the opener to find the door mechanism at the rear center of the door to unlock it. You are looking (by feel) for the mechanism that the unlock rod was attached to. If you cannot get it yourself, you will have to find someone who has some experience with opening doors this way. I have opened mine many times with a Slim Jim tool, so I am positive that it will work, if you use a lot of patience and bend the opening tool to get to the proper area to activate the unlocker. Try to find the little arm by pushing and pulling inside the door with the tip of the Slim Jim tool. That's it.

From what you describe, it sounds like someone tried to slim-jim the door lock and dislocated the metal rod from the lock cylinder mechanism. There are two rods; one to the lock mechanism, and the other to the interior pop-up lock shaft. If the interior lock shaft is going up and down, but the door is not locking and unlocking, the rod to the lock cylinder/mechanism has fallen off (this is very common when someone tries to slim-jim the door for entry). To repair requires the interior door panel to be removed and the rod to be reinserted back into the small L-shaped plastic clip.

lock rod has probably come off from door lock, try to get inside panel off or have someone with slim jim try and reach the rod to unlock the door