Honestly, I would have hated to hear this at 15, and I still hate hearing it at 20, but you haven't even started your life yet. That doesn't make your problems any less legitimate, that doesn't mean you don't have a right to feel the way you do, and don't let anyone make you feel bad for that. But seriously mate, take a step back and think rationally.
At 15 you
a) aren't even fully grown/fully developed mentally or physically
b) you haven't finished high school, in fact, you're not even on your last two years (presumably). Universities, colleges, jobs. Chances are, they won't even look at your current achievements much yet. So it's not like you've messed anything up yet, because that would be essentially impossible
c) Even if you don't make many friends in high school, chances are you're not gonna see any of them once you graduate anyway. Very few people actually establish their adult social lives primarily with people they knew at your age, and honestly, would you even want to?
As for looks, laziness... I had the same problems. But I know this sounds like generic advice, but hit the gym. Change around your style. Experiment with different looks. I'm a well above average looking guy, but guess how I look when I just wear glasses and baggy shorts and old t-shirts and don't style my hair. Hint, I still look like honeysuckle. The truth is, you can't even KNOW how attractive you are unless you give yourself the chance to actually be attractive and put the work in to present yourself well. Trust me, it's way easier than it sounds, and you can get addicted to working out pretty quickly, if you do something you enjoy.
And now's the time to get a **** hobby. I started writing at 18. If I had started at your age, I might be on a near professional level now. Instead I have to deal with a lot of frustration, and slowly watching myself progress while having to deal with my future career and degree at the same time. So, if there's anything you want to do, drawing, writing, animation, whatever it may be... if you're reading this, get started, now, today. Don't "plan" it or feel sorry for yourself for not being great. Just get started now. Might change your life