@yash_gupta that looks like a lens error. Start off by looking through the differences fixes on here. If none of those work, consider replacing the lens. Here are the disassembly instructions [document|30356]
While you work on your camera, 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.
Glad you are going to fix it, no matter what the reason,
Repair is War on Entropy!