Keys suddenly stopped working

I don’t fully understand but,

the other day in my game I could do stuff like open doors and open inventory and more.
I go on today and None of this is working. the ‘crosshair’ is no longer visible at all.

Any assistance? This is really bugging me.

— Something else that was off, was that a few of the starter pack floors i added, had the same thing in a bit up in the air and to the side.