The commercial pilot experienced a total loss of aileron control prior to landing without damage or injury. Visual conditions prevailed. The pilot was level at 2000 feet msl when the airplane entered an uncommanded left roll. He disengaged the autopilot and discovered the ailerons were not responding. The pilot landed successfully at a nearby airport using the rudder to control the airplane. During a post-flight examination, it was discovered that one of the right aileron cables was broken where it ran in a pulley. When moved the pulley did not rotate.
