The student pilot was returning from a solo cross-country flight. He stated that during the final approach to land, with the airplane configured with full flaps, he felt that the airplane was not descending as expected, the speed was higher than normal, and that he would land too far down the runway. The student pilot elected to execute a go-around and applied full power but did not retract the flaps. He stated that the airplane was not climbing and he decided to land on the remaining runway because he didn't think he would clear the trees at the end of the runway. The airplane subsequently went off the end of the runway and struck a ditch and flipped over. The pilot stated that there were no mechanical problems with the airplane. The airplane sustained damage to both wings, the fuselage, and the vertical tail.