It probably hasn't fallen off the track. The part of the window regulator that attaches to the window is probably broken. Mine did the same thing. I took the window and regulator out of the car and epoxied the part back together and then reinstalled it. Been over a year now and still working fine.
Take it off, replace the gasket
The problem may not be that the window has come off the track. I have a '98 Chrysler Concorde and the driver's side window wasn't operating correctly so I took the interior door panel off and found that one of the brackets that anchor the window to the track had broken. I tried to repair it with JB Weld but it didn't hold. I'm going to have to buy a new window.
You purchase a $8,000.00 computer and press "erase codes." If the light comes back on, which I am sure it will, then you repair the problem. Then you erase the code again.
I got an estimate at a local car repair shop and it was $340.91 plus tax for one. The car has two. Could just be your sensor.
You will need to have both computers checked for trouble codes, and then repair the causes of the codes to get the lights to go off.
Take door panel off. and put window back on track.
Have it checked for codes. Diagnose and repair what ever code comes up.
If the door is sagging, due to rusted hinges, have the body side of the hinge welded at a shop. It worked for me and cost $25
You don't repair, you replace.
You dont repair it...you have to replace it.
Purchase a Haynes auto repair manual for your vehicle from almost any auto parts store(about$13.00). Look in either "engine" section or in "tune up" section.
You either get it to a shop, or try and do it yourself, and if you do, look at the other side of the car to look at the formation of the metal. (Don't do it yourself with a hammer....)