Sand down the areas of damage with medium-grit sandpaper, moving the sandpaper in small, circular motions to remove areas of heavy roughness and unevenness.
Sand the same areas with fine-grit sandpaper to smooth the area.
Brush off the area, using the paintbrush to remove sanding dust and debris.
Spread a thin layer of joint compound over any areas that are too low, using the triangular trowel. Continue to add more thin layers until the areas are flush with the other textures. Use the end of the triangular trowel to add dents and creases to match the appearance of the wall where needed. Allow the compound to dry for eight to 10 hours.
Sand the compound-covered areas with fine-grit sandpaper again if you need to adjust the height or make the edges flush with the wall. Clean the area with the brush again.
Paint the area, using the same paint as the wall to create a uniformly painted rough wall.