On July 28, 1999, about 0610 central daylight time, a Cessna R172K, N1092V, registered to an individual, was substantially damaged during a forced landing near Pontotoc, Mississippi. The private-rated pilot and two passengers reported no injuries. Visual meteorological conditions (VMC) prevailed in the vicinity, and no flight plan had been filed. The personal flight was being conducted in accordance with Title 14 CFR Part 91. The flight was originating at the time and was en route to Memphis, Tennessee. About 10 minutes after takeoff, the pilot reported that the airplane's engine lost power and the propeller stopped. According to the pilot there was a "...sudden change engine rpm gage. Noticeably [sic] loss of power. Informed Memphis Center of problem...had reached [altitude] of approximately 2,300 msl. Engine stopped. Landed in cornfield. Aircraft flipped over nose-stopped upside down." Examination of the wreckage revealed that fuel was present in the airplane's fuel tanks. The engine was examined at Jewell Aircraft Engines, Holly Springs, Mississippi, under the supervision of the FAA. Removal of the rear accessory case revealed that the oil pump drive gear was found sheared, causing oil starvation to the engine which resulted in a complete loss of power.