I have an "87 Cadillac Deville that has power windows. The drivers side window has fallen between the door panel. A friend removed the panel and raised the window and it stayed that way for about a week, then it fell again. Does anyone know what parts I need for the door panel or window that will make it stay up?

Welcome to AF, take a look at the problem, glass may have come out of the sash channel, regulator may have broken, hard to tell from here.