Even if they had insurance, it would not cover your car--flood insurance only covers the insured's own property. Furthermore, the school is not liable to you for damage from a flood because the school did not cause the flood--in common parlance, it is an "act of god" for which a person or business is not responsible. The only way for you to have been reimbursed would be if you had your own insurance (e.g. collision insurance) on the car which covered it--that's why people get collision insurance in the first place, to cover them when there is no one else they could hold financially responsible.