Following a normal approach for a night landing, touchdown was made on the main landing gear. The pilot then noticed that the nose was lowering by an excessive amount, and he carried out a successful go around. Examinations from the ground and from a helicopter equipped with a searchlight revealed that the nosegear was inclined at about 30 degrees to the vertical. The position of the nosegear did not alter when the gear was cycled. After all attempts to lower the nosegear were unsuccessful, the pilot elected to carry out a landing with the maingear retracted. He was unable to use the grass flight strip alongside the lighted runway because of obstructions, and chose to land on an unlit strip. The left engine failed because of fuel exhaustion when the aircraft was on final approach. After touchdown, the aircraft slid off the end of the strip and came to rest against the boundary fence. It was determined that the nosegear retract rod plunger had failed from fatigue, resulting in the nosegear being isolated from the remainder of the landing gear system.