Wash the plastic with mild soap and water
Dry it completely with a soft microfiber cloth
Use a plastic polish or scratch remover
Apply a small amount to a clean cloth
Rub the scratched area in circular motions
Wipe off residue and inspect the surface
Repeat if needed for light scratches
Use a baking soda paste for minor scratches
Use toothpaste only on very light surface marks
Sand deeper scratches with very fine wet sandpaper
Start with 2000 to 3000 grit sandpaper
Keep the surface wet while sanding
Finish with plastic polish after sanding
Use a heat gun only with extreme caution on some plastics
Replace the item if the scratches are too deep