During the approach to land, the engine "missed a few times and stopped." The pilot began to trouble shoot the loss of engine power and prepare for a forced landing. He stated that when he checked the fuel selector valve, it moved further to the left which surprised him. During a forced landing to a field the nose wheel collapsed and the left wing was substantially damaged. According to a Federal Aviation Administration inspector, the fuel selector valve was found in the "off" position. The right-wing fuel tank contained ½ gallon or less of fuel and the left-wing fuel tank contained 36 to 37 gallons of fuel. After the airplane was recovered from the field, fuel was added to the fuel tanks. The engine started without hesitation and ran for several minutes at various power settings without any anomalies or issues. An examination of the remaining airplane, engine, and fuel-related systems revealed no mechanical anomalies.