The student pilot of the Cessna 172I stated that following an uneventful local flight, he returned to his home airport to practice takeoffs and landings. During the second approach, just above the runway, the pilot realized that the airplane was "low and slow," so he increased engine power. The airplane's descent rate did not change appreciably, and with the airplane drifting toward the left, the pilot decided to abort the landing. The pilot subsequently increased engine power to full, and kept the airplane's pitch attitude level. Shortly thereafter, the pilot heard the landing gear strike the top of the precision approach path indicator light box. The pilot attempted to "set the airplane down" and the nose landing gear struck the edge of the runway, collapsing it, and resulted in substantial damage to the firewall. The pilot did not report any mechanical anomalies associated with the airplane.