On March 5, 1996, about 1600 central standard time, a Cessna 172, N21662, sustained substantial damage when it nosed over during a forced landing in Valparaiso, Indiana. The private pilot reported no injuries. The personal, 14 CFR Part 91, flight departed Chicago, Illinois, about 1530 with a planned destination of Hamilton, Ohio. Instrument meteorological conditions prevailed at the accident site and no flight plan was filed. The pilot received a preflight weather briefing from a Federal Aviation Administration Flight Service Station. According to the pilot, the briefer reported ceilings from 700 to 2,000 feet, visibilities of one to seven miles with rain and fog, and reported icing in clouds near his planned route of flight. The pilot reported that he experienced precipitation and airframe icing during cruise. He pulled the carburetor heat control to the on position. He descended to an altitude of about 500 feet AGL to maintain visual contact with the ground. He said about 1/8 inch of ice had formed on the airplane and he reversed course attempting to locate an airport to land. The flight controls felt "sluggish." He pushed the throttle to full power and was able to maintain a maximum airspeed of 60 knots. He reported the engine was operating "normally." He selected a field, configured the airplane, and made an emergency landing. During the landing, the nose gear sank into the muddy field, the landing gear collapsed, and the airplane nosed over. Examination of the wreckage revealed the nose gear strut was fractured at the firewall mount and the yolk. The upper leading edge of both wings was crushed and the top of the vertical stabilizer and rudder was crushed in the downward direction. Examination of flight control continuity revealed no evidence of preimpact mechanical malfunction. The engine controls functioned normally. The engine rotated freely and the propeller exhibited minor bending at the tips. One blade was bent forward and the other blade was bent aft. Usable fuel remained in both fuel tanks.