According to a telephone conversation with the pilot, during the landing flare, he realized that his landing gear had not been extended when the "step" contacted the runway. He initiated a go-around; however, the airplane did not climb as expected. The pilot turned the airplane to the right in an attempt to land on runway 21. When it was apparent that the pilot would not make it to runway 21, he extended the landing gear at which time the airplane descended rapidly and impacted terrain. The left main landing gear and nose landing gear collapsed. A post impact examination revealed that the left wing spar and ribs were damaged. Further examination revealed that the propeller had impacted the runway during the first landing attempt. The pilot reported that there were no mechanical malfunctions prior to the accident.