If your BMW windows have stopped working often the culprit is a defective BMW window switch.
A BMW window switch may stop working due to normal wear or if rain falls on the window switch when the window is left open. In both cases, BMW windows won't go up and down and door lock/unlock feature may not work.
The typical cost to change the BMW window switch at the dealership is $350 to $550. The cost to change BMW door window switches yourself is under $100.
If the button has come off your window switch, replace only the buttons with new caps. There is no need to remove the door panel and remove the window switch. See links below under PARTS.
Disconnect the negative battery terminal. The battery in most BMWs is located in the trunk on the passenger side.
Remove the screws that hold the door panel in place.
Pull out the airbag label.
Behind the label, you will find a Torx screw that needs to be removed.
There is also a Phillips screw that needs to be removed.
Watch the following clip to learn how to perform this step.
Disconnect the door handle release cable.
Remove the door switch from the door panel. There are two nuts that need to be removed.
Next press on the retainers and at the same time push the window switch out.
Install the new windows switch. Reinstall the door panel in reverse.