There is a switch just behind the door stanchion for opening the door from the outside. You can open the door and remove the inside panel to get to it.
There is also the inside door opening switch lever that could be causing it too.
And the third thing that could be causing it is a short in the wiring between
the door and the car body.
Roll the window down before you start working on it so you can reach inside
and open the door if you have to.
To trouble shoot it, I'd start with the switch in the door stanchion ( outside
door switch ) by unpluging it and see if the door opens by itself. If it doesn't open then you can try to clean the switch with contact cleaner purchased at any radio shack.
If its not the outside switch, then plug it back in and unplug the inside door
switch. You will most likely have to remove the inner door skin to get to the
plug. Again clean if required for the fix.
Now the not so fun option. The wiring for the door ( windows,switches, mirror)
goes through a rubber tube from the door to the body. You can see it when the
door is fully open and the tube is at the front of the door and connected at
the body. This tube is full of wires that operate the door components.
If you have a wire short it will be here. Don't mess with these wires until
you have made up your mind that the two door switches are not the problem because you can end up causing more than just the door not working, like the
windows not working too.
I would suggest you get the service manual if you decide its in the wiring as
the manual will help you locate the exact wire by color. Its not hard to
trouble shoot the wires but can be very time consuming and its not going to be
fun up under the dash for that long of a time.
But if it is the wire, then you will have two choices. 1) fix the wire in the
bundle or 2) replace the wire harness.
Hope some of this helps you. You'l just have to dig into it some wintery/rainy
day when your not driving the car.
Almost forgot, One other component could be the door latch mech itself.
