First off Prashant2804, welcome to the site!
Depending on the scratch it might not be that big of a deal to be honest. And you might not want to spend the money to get it fixed.
Usually the warranty only covers hardware malfunctions so scratching your screen would not be under the general warranty.
If you have the paid warranty with your provider you can get it replaced that way, but you would probably still have to pay a little to get it fixed.