After a broadside accident, I can no longer unlock and open driver's side door from the outside. I can unlock the door from the inside.
You have several components on your door. Two specific ones that come into play here are the door handle and door latch. The door latch is what actually hold the door closed and where the locking mechanism is housed. There are metal rods that attach the door handle to the door latch. These rods are made of plastic and can easily break in a collision. The rods could have also bent. A mechanic such as one from YourMechanic should be able to remove the door panel and inspect why the door does not lock by inspecting the rods and clips and verifying what needs to be replaced to get the door working properly again.