@luckygaikhwad first start your Tecno in safe mode. Use something like [https://www.youtube.com/watch?v=kP9-aSpFkh0|this video] to get into safe mode. If your touch screen works in safe mode, you know it is a third party app that is causing this. You will have to delete those apps. If it does not work in safe mode either, you may have a bad touchscreen. Time to replace the display assembly.
Since iFixit does not yet have a guide for this, use something like [https://www.youtube.com/watch?v=S2XfesrvU_Y&pp=ygUddGVjbm8gc3BhcmsgNyBsY2QgcmVwbGFjZW1lbnQ%3D|this video] to replace it. Replacement screens are readily available at many online stores.
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!