If you can feel them with your fingernail you are going to have to work them pretty good to get them smooth again. You might need something like
3M's headlight restoration kit to sand down and smooth out the surface. Once done you should apply one of our headlight protection kits to both fill in any remaining scratches and protect them from further damage.
If the scratches were light you might be able to get away with a polish and the headlight protection kit, but from the sound of it they are in rough shape. hope that helps.