How do you repair sandpaper scratch in glass?

2000 grit sandpaper is fine but to polish it as clear as it was you will need Cerium Oxide, and a buffer. I used it to repair my aquarium glass. Sand with specific grit until the entire scratch looks uniform. 2000 grit wet sand, then buff with cerium oxide (use some muscle) until it is crystal clear. Be careful though, if you sand too much in a single spot you will make a small mirrored displacement effect that will need to be "feathered" out. If the scratches are more severe and cost to replace the glass is too much you can have it repaired for a fraction of the cost.