I asked myself if i could do anything, what would I want to do, and really I have no idea.First, before I get to the advice part, a note: Our ability make decisions in the present based on our current emotional reaction to scenarios we imagine happening in the future is an amazing evolutionary advance (compared to, e.g., what even chimpanzees can do), but where it breaks down is that we have only one emotional response circuit, which got reused by evolution for us to evaluate future scenarios, and it doesn't distinguish between the present and the future.
Thus to ask yourself "what would I want to do", and to have no idea, is completely normal. A standard brain limitation. You're in a funk, where you feel sick. You think of some future scenario, something you could do, and check in with your emotion circuit. It says, "blah" and "feel sick". So do you feel like you want that future scenario? No, you feel sick.
So keep in mind that your emotional future predictor circuit is going to be offline while you're in a funk. Being experimental is a reasonable idea: you can go out and try things like going jogging or meditating or getting a hug or getting more sleep or cutting out the caffeine or taking a vacation or painting your room purple or doing nothing for a day and observe whether you feel a bit better or not, but when you imagine doing things you're not going to feel like you'd want to do them.
Another thing I notice is that in your description you describe your feeling bad as a result of not getting thing done ("I can't focus, and this driving me crazy"; "I asked myself what would I want to do"). I'm imaging that you have, in the past, felt good about getting things done, and so when you are unhappy and not getting things done, your hypothesis is that you're unhappy because you're not getting things done.
I suspect that causality may be going the other way: that is, you're not getting things done because you're unhappy, and when your emotional equilibrium is restored, your natural ability to get things done that you want to do will also be restored.
In the meantime, you need to triage your tasks: what are the things that you actually need to get done (to avoid starvation or homelessness, etc.); and what are the other tasks you "should" or want to get done. If you're having trouble with tasks in the first category, ask for help in getting them done from friends and family. For the rest, set them aside and don't worry about them until your emotional equilibrium is restored.
When you're in a negative emotional state, you need to first get to neutral. Once you're in neutral, working on aspirations and productivity tools are ways to then get to positive. But you can't go from -10 to +10 in one jump. You need to get to zero first.
I went through a period of depression, so I'm quite familiar with the feeling of not wanting to do anything, and being unhappy about it. I found therapy enormously helpful in getting myself up to zero. Eventually I got to zero and stopped going to therapy because I had outgrown it.
So this is my advice, since I've been in this situation and this is what worked for me: get therapy. Recognize that the goal of therapy is to get you reset, to get you up to zero. Once you're at zero, and start feeling like doing things again, that's the time to pursue GTD or whatever that you find useful. Therapists are typically not going to help you much getting past zero, but getting you out of your negative condition and up to zero is something that they're really good at.
Please feel free to email me at andrew.wilcox@gmail.com if there's anything you'd like to ask or tell me privately.