We may have two possibilities that I can think of.
Something got stuck/jammed/wedged in the door or the mechanism. Sometimes it's the seat belt or a toy or other things!
There's a problem with the mechanism it'self.
My first approach would be to try the interior locking lever (on and off a few times) and do the same with the key from the outside. It might be that the internal rods have not moved far enough to let things loose or the rod for one or the other "unlock" has come loose. You may have tried this already (probably). This would be the easiest thing if it works!
The "wedged" possibility.
This will require two people, one to hold the handle "open" constantly (try the interior [with the window down] and exterior handles one at a time). The "handle person" needs to stay out of the way!
#2 person is going to lay on the seat, if possible. Depending on your situation something protective might be draped on the doors interior. Maybe a towel, blanket, or foam. #2 person will select a strong flat space on the door. With the handle open (#1 guy), #2 guy is going to deliver a good swift kick to the door (closest to the exterior handle end of the door).
After several attempts at this, abandon the suggestion. More kicking and screaming is going to probably tear something up bad!
Now we have the mechanism possibility, this will most likely be the hardest to get to. It's sometimes difficult to do this with the door open. You will have to take special care in getting in there. I've seen people even remove their seat to gain better access.
Here's one of our "Repair Guides" (from the top right of our pages) that may guide you along:
Around here are: "you go get it yourself" auto salvage yards!
Many of them don't care what you do out there, but an "excuse" might be that you are getting a window motor. Just to play it safe with your car, you might could find one like yours in the salvage yard and see exactly how the panel(s) come off. Sure, it's "time", but you are not spending any money!
Keep us posted with progress.
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Thursday, January 7th, 2021 AT 6:48 PM