Bad Luck

Does anybody ever feel like luck is never on your side? Like, you go above and beyond to get something you want and never get it or work your ass off and still not get it. Lately, i have had this black cloud following me, for example, i have been studying for this accounting exam, totaling 14 hours, and i still feel like i bombed it. Another example is that you think you have made great, trusting friends, but then they just turn their cheeks when you need them. My friends here feel like they can say anything to me and that it will be a secret or that i will try hard to help them get through it. But when i need help, they just dont give a shit and say, well i dont have time. Im just going through a bad phase in my life and was wondering if anybody has gone through one of these. How did you break out of it or is it still around with you today?