I went through a period similiar to this a couple of years ago, on the back of a failed relationship I shut myself in and quit College, went on the dole (unemployment welfare) and sat around playing video games for a few months. Got to the point where I was demotivated about everything but after a while of doing nothing and not being bothered I got fed up and started applying myself and got an oppurtunity (working for the welfare office ironically enough) and it was much more rewarding than sitting on my ass on video games 12 hours a day.
You won't learn to apply yourself from an internet board, you won't learn what you want from life here, only thing I can say is if you fall into that cycle, it can be hard to get out of because you become used to it. It's your choice though, you can go through like doing what you're doing now if it's what you want or you can do other things, from my point of view it was the experience of living my life like that for a while that told me I should get a career, earn money, look to move out or move abroad.
You can deal with it in different ways, medication, talking to people like a Doctor or in my case have somebody believe in me. But only you can do anything about it, all the advice in the world won't mean anything if you don't do it yourself.