If your scratches are very bad, it is useless to try things. If it is moderate, you can try using toothpaste. Take a clean, soft lint-free cloth and moisten it, using the cloth wrapped around one of your finger. Then apply a minute quantity of toothpaste on the cloth and wipe radially on the DVD. Don't apply too much pressure, else you will be scratching the disc more! Then, clean the DVD using just water using the same cloth, but make sure it is clean and no toothpaste. Worked a lot of times for me. I used to do this when I got scratched discs from the movie rental store