If your car's ceiling has dropped, there are a few things you can do to try to fix it. First, check the ceilings in other cars to see if they have also dropped. If so, then the problem may be with the design of the car and you may need to get a new car. If only your car's ceiling has dropped, then there are a few things you can try.
One thing you can try is to push up on the ceiling from underneath. This may help if the drop was caused by a loose panel or piece of trim. Another thing you can do is to remove any loose panels or trim and reattach them with adhesive or tape. Finally, if your car has an adjustable roof, you may be able to raise it back up into place.