THE PLT, 3 ADULT PAX & A SMALL CHILD WERE RTRNG TO THE ARPT AT NIGHT. THE PLT WAS TOLD TO FOLLOW 2 OTHER ACFT; HOWEVER HE ENTERED TRAFFIC INCORRECTLY AND WAS TOLD TO GO AROUND. AFTER TURNING TO A DOWNWIND LEG, THE ENG LOST POWER & THE PLT DECLARED AN EMERGENCY (MAYDAY). HE MANEUVERED THE ACFT TOWARD THE ARPT, BUT BEFORE REACHING THE RWY, THE ACFT CRASHED IN A LEFT WING DOWN, NOSE LOW ATTITUDE. IT CAME TO REST & BEGAN BURNING AFTER IT TRAVELED ABOUT 180' FROM THE INITIAL IMPACT POINT. ALL PAX EGRESSED FROM THE ACFT, BUT THE PLT COLLAPSED BEFORE HE ESCAPED. THE RIGHT WING & CABIN/COCKPIT AREAS WERE EXTENSIVELY DAMAGED BY FIRE. A POST ACDNT EXAMINATION OF THE ENG DISCLOSED NO EVIDENCE OF ANY PREIMPACT MALFUNCTIONS OR FAILURES. WHEN THE FUEL SELECTOR VALVE WAS CHECKED, IT WAS FOUND POSITIONED BETWEEN THE LEFT & RIGHT FUEL TANK SETTINGS. THE HANDLE FOR THE FUEL SELECTOR VALVE WAS NOT INDIVIDUALLY LIGHTED; ITS LIGHTING SOURCE WAS THE OVERHEAD CABIN LIGHTING. ONE PAX RPRTD HEARING THE SOUND OF A STALL WARNING HORN BEFORE IMPACT.