First thing to do is check all the fuses, if none are blown, check for power at the switches, if the power is at the switch then check for power to the actuators/motors with the switch depressed. After checking and repairing anything that you find wrong then you can pull the door panels and get the motors/ actuators out. They are riveteted in usually and you will have to drill or cut the rivets to get them out. Be sure to support the window glass before removing the motor/ regulator or it will fall and likely break.