ON SUNDAY, OCTOBER 20, 2019, APPROXIMATELY 3:10 PM I GOT INTO MY 2018 TOYOTA COROLLA, THE CAR WAS STATIONARY IN PARK, AND WAS NOT RUNNING ON A FLAT SURFACE. I REALIZED I FORGOT MY WALLET SO I GOT OUT OF THE CAR AND LEFT THE DRIVER'S DOOR OPEN. I RETRIEVED MY WALLET WITHIN 1 MINUTE AND WHEN I CAME OUT MY CAR WAS ROLLING SLOWLY ON THE FLAT DRIVEWAY WHERE I PARK EVERY DAY. I TRIED TO GRAB THE DOOR HANDLE TO SEE IF I COULD JUMP IN THE CAR TO STOP IT BUT IT PICKED UP SPEED AND WENT DOWN A SLIGHT INCLINE ACROSS THE YARD. THE DOOR HIT A TREE AND THEN THE CAR LANDED IN BUSHES. MY NEIGHBORS CAME RUNNING OVER BECAUSE THEY SAW THE ENTIRE INCIDENT. I WAS ABLE TO GET INTO THE CAR ON THE PASSENGER SIDE AND I STARTED THE CAR'S ENGINE SINCE IT WAS NEVER TURNED ON AND DROVE IT OUT OF THE BUSHES BACK ONTO THE FLAT DRIVEWAY. THE CAR ROLLED WHILE THE GEAR WAS IN PARK AND WAS NOT RUNNING. EVERYONE IS NOT SURE WHY THAT WOULD HAPPEN. I'M ASKING TO SEE IF THERE IS A PROBLEM WITH THE TRANSMISSION OR THE GEAR SLIPPING OUT OF GEAR. I CALLED MY INSURANCE THEY FILED A CLAIM BUT STATED IT WAS VERY STRANGE FOR THE CAR TO HAVE ROLLED AND TOLD ME TO FIND OUT IF THERE WAS A RECALL, ALSO THE ADJUSTER SAID IT WAS VERY STRANGE AS WELL FOR THE CAR TO ROLL IN PARK AND NOT RUNNING. THEY SUGGESTED IT MAY BE SOMETHING WITH THE COMPUTER SYSTEM.