The motor is part of the regulator assembly. You could test the motor by putting 12 volts directly to the terminals on the connector going to the motor. Put the window halfway down and unplug the motor from the main harness before testing. If it's truly bad, you should just swap out the whole regulator assembly. They are under $100 on ebay. Just search for 2000 Kia Sportage window regulator.

There are two screws holding the window to the regulator. Take those out and carefully pull the window out of the door. You'll probably have to tilt it forward somewhat to get the angle needed to pull it out, and you may have to have the window partway down when you start. The motor portion of the regulator is just held in by three nuts and the track is held by two. It comes out easy enough once you remove them. Put the new one in and, replace the window and button it all up. However, I seriously doubt the motor is the problem unless you burned it out by holding the switch too long when the window was open or closed fully. I only had to replace mine because the cable snapped. The motor was still fine.