The student pilot related that she was on her second solo flight and had planned to perform some touch and go landings then depart the airport to the south for some air work. Upon completion of the planned air work, she attempted to find the airport and stated that she had difficulties finding the airport and possibly overflew it. When she found the airport, she said that she became concerned with the aircraft's fuel status and about traffic around the airport. She stated that she got 'low' on her approach and then noticed that the engine '...did not sound right.' The pilot stated: 'I know that I was too low because both VASI lights were red. That is when I must have pulled back on the controls and stalled the plane.' An airworthiness inspector from the Scottsdale (Arizona) Flight Standards District Office (FAA) inspected the aircraft after the accident and could find no reason for the engine to have lost power.