If you ever look out your window and realise that there is a scratch affecting your view, do not panic. In many cases, you can repair the scratch to the point where it is no longer noticeable. With a few supplies from the grocery store, you might be able to remedy the issue if you are willing to put in the effort.
Spread on some toothpaste over the scratch. Do not use a gel paste. Let it dry for about 30 minutes, so that it gets hard.
Wipe the window with a soft cloth, such as a cloth diaper. Once most of the toothpaste is off, wipe back and forth in one direction to buff the scratch. If it is still there, then it was too deep and you need to try another method.
Mix ground mustard with vinegar to form a paste. It doesn't take a lot of vinegar to create the paste. Spread this on the scratch and let it dry.
Wipe the scratch area and buff as before. If this doesn't remove the scratch, use cerium oxide. You can pick this up from a jeweller. Make a thin paste with water and spread it on a buffing pad attachment that will fit on your drill. Buff the glass with the mixture to remove the scratch.
If nothing else works, try using a scratch kit for an auto windshield. Follow the directions on the box to try and remove the scratch. It comes with a window buffing agent.