Most electric rear view mirrors use two motors to move the glass, one for up and down adjustments and one for left-right adjustments. The control switch has a selector portion that sends voltage to the left or right side mirror. With the ignition ON but the engine OFF, roll down the windows and operate the mirror control switch through all functions for both the left and right side mirrors while listening carefully for the sound of the electric motors running in the mirrors. If the motors can be heard but the mirror glass doesn't move, there's a problem with the drive mechanism inside the mirror, necessitating removal and disassembly to locate the issue. If the mirrors do not operate and no sound comes from them, check the 
Fuse. If the fuse is OK, remove the mirror control switch from the dashboard and have the switch continuity checked by a dealership service department or other qualified automobile repair facility. Test the ground connections, and if the mirror still doesn't work, remove it and check the wires at the mirror for voltage. If there's no voltage in each switch position, check the circuit between the mirror and control switch for opens and shorts. If there's voltage, remove the mirror and test it off the vehicle with jumper wires, replacing it if it fails this test.