You're only 17, you got your whole life ahead of you man.
Itishe made a nice point. It's not that you feel lonely because you don't have anything to do. I was at home too yesterday, alone. The difference is that I choose to do so because I wanted to be fit to go skateboard a contest in half an hour right now.
I really think you should choose something purposefull to do with your life. Something you can express yourself in. And don't expect to be a master at it to soon, just choose something you like, commit to it, keep doing it untill it starts to become more and more fun.
Remember: "What you think about is what expands"
At first, there is only a spark of interest in what you want to do, but if you commit to do whatever it takes to get the basics down than it's going to become a great hobby and the rest of your life will follow.
Don't get discouraged if you see other people doing better while you are struggling with what seems the most simple stuff. They've been doing it for a long time and all started as a beginner too.
First, think about different things and decide something that you like.
Next, go do it, as fast as possible.
Here's a great article to get started and keep building, creating the habit into a hobby and eventually a lifestyle
It's usefull for any kind of habit you want to have
http://www.bristollair.com/inner-game/identity-and-beliefs/implementing-a-habit.html
Have faith