Have you ever seen anything like that? Please see video:

https://youtu.be/g5YcAbvpR1I

One day I noticed I have problem choosing some items from menus if they are located at certain height from the top of the screen. I needed to scroll the menu down or up to choose those items. I never had that problem before. Then I thought of trying some drawing app, and voila. There is a stripe of screen that does not work. What do you think of that? Can I do anything about it?

I may add that nothing ever happened to the phone, like falling from some height or getting into water.

Update to the latest Firmware and perform a factory reset in recovery after that.

wipe data/factory reset in recovery (this will delete your data/settings):
- Power off and then press Power and Volume-up together for around 10 Seconds
- be sure that the little arrow point on recovery (select with volume up, enter with volume down)
- Then the open android with red triangle+"no command" is shown - press Power and Volume up together again
- Select Wipe data/factory reset with volume keys, confirm with power
- After factory reset select reboot system now

If that don't help please ask your seller for repair or replacement.