Drive three or four fat nails (using pilot holes) halfway in up and down the door jamb where the door comes to meet. Cut the heads off leaving about 3/8" (1 cm) protruding. Drill holes to match in the door edge so the nail ends engage the door when the door is closed.
Tornado victims: Do not rush to rebuild. Take your time and look for and get a good contractor. Or consider selling the property and moving to a home that is ready to live in.