My driver's side door won't close. The part of the lock that wraps around the pin has closed up. The problem is: how do I open the latch so it will go around the pin?

Pull up on handle. Turn key as if to open. Take screwdriver and press down on the lower jaw of the latch. Wala, the door opened.

nope..tried that didn't work..

Have same issue. This is old but maybe will help others. Is the latch mechanism frozen? Is there tension on the latch? There's a spring and if it breaks the latch falls in the closed position. Test a working one to see the difference. You have to remove door panel and see if the springs gone or broken, or check the rods in there to make sure everything is connected. I heard it was easier to replace the whole handle as opposed to just the spring.

Larry you saved me big time, it worked like a charm. Thanks pal

What if you dont have a key to unlock you lost the key and the door wont shut

Pull handle & push the latch upwards it should reset. Here’s a video on it https://youtu.be/OWXHUcy0klQ

Thank you all for the answers I have a 2001 yukon 207K miles. Im in Chicago and temps dropped to -3 my driver door would not close. I held outside door handle open, used a screwdriver to move latch and it worked perfectly. That you all for the tips.