Ok...
I'm not popular, everyone at my school hates me.
98% of kids are not popular. they are just the random kids you see. you surely aren't alone in this situation. everyone hating you is probably an exageration, but if people have a particular reason to hate you, its a good time to be honest with yourself and reform.
ignore all those things about not being yourself. you can maintain your interests, but don't stunt your growth by trying to be "who you are". Make a honest change for the better, even if its in only small ways. baby steps! You'll find you can change who you are drastically, and it will not be an act, but a real change, which is a good thing. its growth, its progress. think in those terms. your bad situation will yield to time.
I'm no good at anything, at all.
Lies! you are good at something, but i bet that you don't percieve value in it. for instance, I secretly know an amazing amount about insects (don't get me started!), but i would never put entomology as things i'm good at. You also need to try stuff, but i'll get into that one later.
I don't leave my room most of the time.
yeah, that sucks, my sister is like that, but she enjoys it i guess. You can always go outside though, expore the woods, and do stuff. no point in sitting around doing nothing. You can easily change this room issue.
I have no social life apart from MSN.
your better off than me. I don't even have a social life on the internet. thats about as low as it gets! i have maybe a very small tight circle of friends that i only really get to talk to rarely, because i live in a ghost town next to my hometown where all my good freinds lived (or they moved away). as a result, i've been trapped in this miserable house for the past few months.
then make one. I partake in the worlds greatest hobby, known as model railroading. Its really fun once you get started, and the skills you learn are useful later in life. I'd post pictures of my work, but this isn't the thread for it. I need to update my site on my layout to.
I've also built many Ships, and airplanes, and i've tried other things. Its all good fun when you get it going. I find trains to be the best though, since you get interaction with them, and you can keep running them. In fact, i took up the train hobby for many of the same reasons you feel so sad. it definitely helps when you have something to be proud of. Its also an endless hobby, you can always add more detail.
I have loads of other hobby ideas, many that i've personally tried out, and i can get you started really easily if you'd like.
Am I worthless? Is there any reason to me?
You are not worthless, you serve a purpose, even though at school nothing seems to work out. You have to remember that this is only a small part of your life even though it feels like it has been dragging on forever, and even then, things are likely to change very soon. just remain positive, and keep trying to improve yourself. In time, things will get better, I garuntee that.