Hi there and welcome to Scarleteen. I'm sorry to hear that you're feeling a lot of frustration around wanting to masturbate and that not working for you right now. Let me firstly start by reassuring you that there is nothing
wrong with you, this is an experience a lot of people deal with!
It sounds like you've been doing some reading and research around this already, so you might have come across the concept that one of the most important sex organs that you have is your brain. This is key: our mental state of mind is a really important part of whether we're going to feel aroused by something, even if that thing has worked for us before. What I'm hearing in your post is that you're feeling really stressed about wanting to feel pleasure from masturbating. Often it is this stress and putting pressure on ourselves to achieve pleasure, that can put the breaks on any arousal happening. Our brain says "Sex?! We don't have time for this! We're stressed!", even though our stress is about not feeling arousal and sexual pleasure, unfortunately our brain doesn't know the difference.
You can read more about this in this article by Scarleteen's founder, Heather, Sexual Response & Orgasm: A Users Guide
- to quote directly from them: "If we're sick or stressed out, tired, preoccupied, or feel guilty shameful or upset, it's hard to feel sexual pleasure, let alone orgasm. Cut yourself a break when that happens. Go do something else you enjoy. Honor what your body is trying to tell you it needs. Just like it's not a good idea to eat when you aren't hungry, it's not a good idea to have any sort of sex when you're not interested or when your body isn't up to it. The beauty of sexuality is that it is with you your whole life: you can't miss out on anything. You have your whole life to enjoy it. "
Whilst it might be hard to be patient about this right now, giving yourself some space, time and self-compassion around this is the best thing that you can do for yourself. After giving that to yourself, try approaching self pleasure as an exploration, rather than a mission with a defined end goal (eg. orgasm). See if you like a certain kind of touch, sensation, imagining certain scenarios, and whether you find these things pleasurable in their own right, rather than trying to make them take you to that end goal. This will help you understand yourself and gently guide you to what you enjoy. We have some great articles on here to explore Scarleteen once you've given yourself a bit of a break.
As an aside, I just need to note a couple of things about asexuality - I know you are feeling really stressed out about wanting to feel arousal at the moment, however please take this gentle reminder that it is important not to lump being asexual together with the concept of something being "wrong" with you. There is nothing wrong or defective about people on the Ace spectrum, it is a sexual identity as valid as any other. Also, experiences of asexuality vary widely, and some asexual people do enjoy masturbation, whilst others do not. You can learn more about what being Ace can be like for folks here: Just the Basics, Ace: An Asexuality Primer