top of the screen is at the bottom

I think you may be seeing a feature called Reachability.

Bring the screen within reach on iPhone - Apple Support

Maybe the iPhone is upside-down?

What, exactly, does that mean? Could you post a screen shot?

(You know what, Idris? but keep your lips sealed. Demo has a brand new crystal ball. Mine has been on strike for several months and is an obsolete model. I will also have to decide to buy a new one)

Giulio :-)

Excellent deduction, Demo!

Or, a lucky guess. :) I hope will find out if the OP responds.

Ha! I knew he had an edge!