This depends on the depth of the scratch ,light scratches can be improved with a high speed "mop" the type your use for cars ,with a cutting paste. This needs to spin very fast to make any difference. Deep scratches won't look any better, they cam be filled with clear resin and polished flat. If it's a car wind screen with scratche's it might have to be replaced. On a house window with a patch of scratches from trying to remove hard bird droppings , you could cover them with a glass decoration[ coloured birds ]etc.