During a cross country flight the pilot of a Cessna 150G executed a forced landing after a complete loss of engine power. During the landing the airplane nosed over substantially damaging the firewall and vertical stabilizer. According to the pilot, after leaving his departure airport, he stopped at two other airports prior to proceeding to his final destination. Once he arrived at his destination airport, he was unable to turn on the runway lights and began to orbit the airport. Approximately 10 minutes later, the engine began to "roll back" and lost all power. The pilot estimated that he had operated the airplane for 3.2 hours prior to the loss of power and that all of the flights had been operated at 3,000 feet. He stated that the fuel burn had been 4.2 gallons an hour in accordance with the pilot's operating handbook (POH). A review of the Cessna 150G POH revealed that 3.24 gallons was required for the three, engine start, taxi, and takeoff sequences. A review of the airplane's engine hour meter and maintenance records revealed that the airplane had been operated for 4.6 hours. Fuel burn calculations derived from information in the POH, the pilot's stated fuel burn, and hour meter information revealed that a total of 22.52 gallons of gasoline would have been consumed. According to the POH, total usable fuel was 22.5 gallons. A postaccident examination by an airframe and powerplant mechanic revealed no evidence of fuel in either the fuel lines or fuel tanks.