@pritikumari7545 it may have failed. Place your phone into safe mode and see if that allows the touch screen to work again. If it does, you know that it is a third party app that causes this. In that case you will have to delete the Apps that you recently desalinated until you find the one that caused it.
If it still does not work in safe mode, time to replace the display assembly, since the touchscreen is part of that. Since iFixit does not yet have a guide for this, use [https://www.youtube.com/watch?v=dGJd1_WQNCI|this video] to replace it. Replacement displays are readily available at many online shops. Once replaced, re-evaluate your touchscreen. Let us know what you find out.
While you work on your phone, take lots of pictures. Once you are done with it, take those pictures and create a guide for iFixit. That will help the next person that has a device with the same issues as you do. It's easy and fun to create these guides. https://ifixit.com/Guide/new The iFixit community will appreciate this.
Repair is War on Entropy!