How can you remove scratches from the screen of your Game Boy advance

One way is to use toothpaste. Put a very small dab over the scratch you want to fix then rub hard with a soft cotton cloth. If you're patient, it will remove shallow scratches and lighten deeper ones.

Another method is to use a CD scratch repair kit. It uses a similar method to remove scratches.

One way to get rid of really deep scratches would be to use some sort of polish (like metal polish or polish for hard plastics). Unfortunately you will occasionally have to re-polish your screen from time to time.

If the scratches are too deep or too severe, try looking online for a replacement screen cover. They run about $5 and cost much less than buying a new system.