Long story short: (2005 Ford Focus ZX4) Son rear ended another car (no injuries). Most damage to bumper, grill, radiator support, headlights, all of this can be fairly easily replaced/repaired. Car is drivable as is, however, after the accident, drivers seat belt does not extend or retract and air bag light on the dash is illuminated. Air bags did not deploy. Does the seatbelt need to be replaced or does something need to be reset? Why is the airbag light on?