How do i roll up my windows if they are stuck down?

i have eletric windows on my 91 4Runner. The have been going out one by one. My driver side is stuck down. How do i put it back up? and what could it possibly be?

Take the door trim panel off so you can get direct access to the motor. Disconnect the motor's connector and apply 12V DC to the motor. If nothing happens reverse the polarity of the wires. If you can't get the window to move it would indicate the motor is dead.

If you don't already, get your hands on a set of schematics for your truck trace the power back through the switches. Since they did not all go out all at once doubt that its a global problem to all windows but with each.
fourwd1 is correct in applying 12v to the motor connections. there are limit switches the open the circuit in each direction of travel if one of those are misaligned it will not allow the motor to run, this is where the schematic will come in handy.