Disclaimer: I am not even 19 yet. So take this comment with an ocean full of salt.I have failed in my life more times than I can remember. In fact, everything I have ever done has been a failure at some level or the other. All of my plans to get myself out of the rut and actually do something with my life have failed.
I have so many shortcomings that I can't list them in a book let alone a comment, but pitfall has taught me something. Never ever give up. It is something so cliched, but somehow it's the essence of life. All of the advice above me has taught me a lot, but the thing is that while implementing that advice you will fail.
You will fail again and again and again. I really hope that life has dealt you a fair hand, but sooner or later you will feel like everything is lost, and that life is no longer worth living. Don't listen to yourself at that time. Give yourself time, and just get up and start moving. I really do hope that you don't have to experience this, but it is quite true.
It is something so obvious, but something really hard to do when you are in that situation. I really hope that you never ever go through that pain, but whenever you do just remember that life is worth far more than what we can ever imagine.
Other than that rather obvious piece of advice I would suggest that you should surround yourself with people who care about you. Find your family. It doesn't matter if it is united by biology or sheer love, but you need people in life to love you and give you those small things that we all take for granted.
I know just how corny this sounds, but I wouldn't be alive today if it weren't for this. Whenever you know that you are loved unconditionally it gives you a sense of security and peace that no amount of money in this world can buy. Those people are the ones that make your life worth living, and help you to achieve your goals.