@armghankhan if it is the same area that fail in landscape as well as portrait mode, it would appear as if your touchscreen has failed. I would suggest you replace the complete assembly. It is easier than a glass only repair, unless you have all of those tools needed and have the experience to do a Glass-only repair :-) Use something like [https://www.youtube.com/watch?v=0KDZZrGdMOo|this video] to change it. Replacements are readily available. Do an online search to find a vendor that meets your standard.
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 the same problem 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!