rover 400 diesel?

my s reg rover400 diesel is in spain and last week i went over a speed bump fast and the front banged on the floor. when i turned the car off it wouldnt start again the srs light i think it is on the steering wheel lit up and it makes a ding ding ding warning noise,i left the car for about an hour went back and it started
after this i drove around for 3 days as if nothing had happened drove to the airport and left the car,however a week later when my wife tried to start it the problem has returned and it will not start anyone any ideas?