Ooops - sanded lined painted walls

| I had perfect lined and painted interior walls.. until I decided to | remove a few marks by sanding over them then painting. On stepping back | to inspect I saw that you can obviously see the sanded areas - they | look like big patches of scratches to the lining, which they are! Any | ideas on a quick fix?

Re-do the sanding with progressively finer sandpaper. Remember to take out all the scratches produced by the previous sanding at each stage, or you will get "Highly polished deeply scratched" as I learned as an apprentice years ago.