Zero Motivation and Zero Passion

I don't know what's going on with me, but these past few months have been absolute hell. This was a gradual process, but a very fast one at that. I have absolutely ZERO motivation in anything, and almost zero passion in anything -- including art and writing, which I absolutely love and used to spend hours, sometimes even all day doing nonstop. This is beyond "artist block" or "writers block", this isn't even a block at all. I don't hate these things. I still love them. But I just don't feel any passion towards them anymore. I've tried to get back into my usual groove, but it's almost painful to do so and I stop after five minutes because there's just. nothing. there. This lack of motivation doesn't just spread to things I previously used to love. I shower about once or twice every 8-10 days, I don't change my clothes not even my underwear until then, I barely brush my hair, I only brush my teeth at night after forcing myself to get up for hours but half the time I can't even bring myself to use toothpaste or to wet the fricking brush, I'll try and put deodorant on but half the time I just see it as "I'm ugly and I'm gonna smell bad anyway so what's the point", I completely failed my first year of high school because I don't know how to study and can't bring myself to even do my homework and "what's the point when I'm not going anywhere", I used to get so upset whenever I wasn't invited to things with my best ((and only)) friend because of my social anxiety disorder and now I still feel so incredibly rejected and sad but at the same time I don't feel anything and I see no point in making plans. I don't see the point in anything. I just want to lie in bed all day and do nothing, either sleeping or just watching anime or YouTube because I can't bring myself to do anything otherwise. I'll sleep for up to 14 hours at night, and sometimes I'll even take another nap during the day, so I'm constantly tired because I'm sleep drunk but I can't do anything else. And I don't feel chronically sad or angry or anything. But I just feel empty all the time. I could feel the strongest emotion but I'd still feel empty inside, and I still wouldn't care because I seem to have lost my ability to. I'm not going anywhere in life. I'm not going to succeed, I'll be dead before the time I turn 25. What's the point in trying if my fate is already doomed. If you can even call it fate, I call it an embarrassment, a failure, because that's exactly what I am and how I see myself and I know that that's how other people see me as well. I get angry at myself for how lazy I've become. A couple weeks ago I took a knife and put a scratch in my elbow because I was having a panic attack over the whole thing, I wasn't thinking straight and I didn't know what else to do. It didn't bleed. But it broke skin. I hsve a scar there now. I'm not suicidal. But at the same time I don't think I would care if I died right now. I don't feel this fear of the unknown that I used to anymore. I don't cry like I used to anymore, or show emotion hardly at all. I don't want to die but at the same time I don't feel like living. It's half and half. I just don't know what to do. I always knew that my life was going downwards but now I know that I am a failure and a disgrace to the human race because of what I have become. I'm not sure why I sent this whole thing, but say what you will. I just needed to vent I guess. I feel a little better now. As better as I'll ever feel, anyway.