MY VEHICLE'S IGNITION SWITCH SHUT OFF, WHICH CAUSED ME TO LOSE STEERING. WHEN I CRASHED, THE AIRBAG FAILED TO DEPLOY. I WAS DRIVING IN A LARGE PARKING LOT AND WENT OVER A SPEED BUMP. I WAS KNOCKED OUT BUT THE POLICE REPORT INDICATED THERE WERE NO SIGNS OF BRAKING OR STEERING. I TOOK MY IMPALA TO THE GM DEALERSHIP OVER 12 TIMES.