Shortly after takeoff, during the initial climb, the pilot stated that he perceived that the airplane’s engine noise was louder than normal. After ensuring that the pilot and passenger side windows were closed and locked, he decided that he would decrease the engine throttle slightly to diagnose the sound. When the pilot reached for the throttle, he inadvertently grabbed the mixture control, and after pulling it back, the engine lost power completely. The pilot attempted to restart the engine twice, but both attempts were unsuccessful. As the airplane was approaching a tree line, and only at an altitude of about 300 ft above the ground, the pilot decided to turn back to a field that was near the end of the runway. The pilot subsequently landed the airplane off-airport, and during the landing roll the nose landing gear encountered a rut. The airplane subsequently nosed over, resulting in substantial damage to the airplane’s rudder and wings. The pilot reported that there were no preimpact mechanical malfunctions or failures of the airplane that would have precluded normal operation.