If the window on your Mini Cooper has stopped opening when you open the door then you may need to reset the window motor and window position sensor in order to make it work again. The window sensor and motor detect that the window is in a different position than it actually is. Resetting it will allow it to start correctly tracking the window again. Sometimes this procedure can also help when a window is stuck in position and does not move when the switch is pressed.
Insert the keys and turn on the ignition. It does not matter whether you start the car or not.
Put the window all the way up (if you are able).
Press and hold the window switch in the up position for 10 or more seconds. Do this with the door closed.
Open the door to make sure the window drops as it should. Close the door to make sure it goes back up again.
If this does not solve the problem then it may be one of the other issues with Mini Cooper windows.