2000 Chevy Silverado Drivers side window

If the motor is working in the down position, it is most likely good. The window movement is changed by changing the polarity to the motor. Remove the door panel and see if there is power to the motor. Check for power in both directions. IF there is, then the motor is bad. If there is only power down, replace the switch. If you switch the wires (only 2 of them) to the motor, the window should go up when you press the down button.

Let me know if this helps or if you have questions. It sounds confusing but is really simple.