When you play your favorite game after a while you disc will scratch but say like in ten years and still playing it how can you buy a decent copy of that same game

Try an auction site and search up your disc name. Or search up the name of the disc, put down the year and it should give some online stores. If you can't buy from online stores, I'd suggest putting down the name and a store that you first bought it from or where you think it would be located.