Dad my bedroom door handle won't stay up so the door won't shut. How do I fix it?
So the first part I can answer - see that hole on the right under the handle?
There should be a little screw bit in there you can tighten or loosen using an alen key. It looks to be missing.
Odds are it just fell out (look on the floor nearby) - sometimes years of motion just does that.
As for the second part, no idea XD