I feel like I'm going crazy over these missing things of mine. As I search for them I only find more things missing. I am actually on the verge of accusing my family of theft from how completely I've searched and how I find nothing, except the things missing don't even make that much sense for a thief.
In my experience, don't accuse them and don't get mad. You'll find whatever it is exactly 3 seconds after you've made an ass of yourself.
What you should do is take basic steps to prevent theft in the future. For example getting in the habit of only storing your things within your own space and organizing your space so you can tell when something is missing. If you continue to be suspicious you could start taking more rigorous steps like taking pictures of things to tell if they'll be disturbed, locking your door when you're away, or hiding things that you expect to be stolen.
Its worth pointing out that most families have a white noise of moving each other's stuff around in the public parts of the home. I know I lost so many things as a kid because my mom would move them from one part of the house to the other in the course of cleaning. And in some families, people will casually enter each other's rooms to borrow (or "borrow") things and not think of it as theft. Kind of depends on what kind of family you have.
Edit: forgot the simplest step. Ask "have you seen my _____ anywhere? I don't remember where I left it." Its not an accusation and sometimes you'll get a helpful answer.