Hello and welcome to Just answer.com, Super mechanic here. About your vehicle.
There is a relay for the power windows. It is on the left side of the dash, facing the door. You can open the door to get to it. It should be behind the panel. You want to check for power to it. Also, see if there is power at the main switch.
The following circuit test sequence determines whether or not voltage is continuous through the body harness to switch.
The following test should be performed if all windows do not lower when the top switch is in the down position.
Check for battery voltage at pins C1, F1 and D1 of the window drop relay wire connector. If OK, go to Step 2. If not OK, check the circuit breaker and fuse or check for a shorted or open wire. Repair as necessary.