Yeah, it bothers me too and I think about it a lot. I've tried reading eastern philosophy and various opinions on that, but they all seem like rationalozations of people trying to comfort themselves.
One thing I want to tell you - don't think that there's something wrong with you because you are afraid of death. Many people cope by trying to convince themselves that "death is okay, and may, in fact, be a good thing", and it all sounds deep and wise, but it doesn't really make any sense. It's okay to be scared/frustrated/angry when thinking about it.
From everything that I've read and thought about, I've concluded, that if we cut the shit and ignore all the pretentious philosophy and rationalizations, all it comes down to is "try not to think about it and enjoy living your life right now".
When you are a kid you don't think about death, but once you comprehend it it is shocking and depressing, but over time I guess you just get used to the thought, and learn to focus on work/friends/etc and enjoy the life that you have.
I think that humans will cure death eventually, and it makes sense to do everything in our power to fight it. I suggest you check out Eliezer Yudkowsky and the transhumanist community for a lot of interesting ideas on that(like cryonics).
Once you have done everything in your powers to avoid dying(healthy lifestyle, wise choices, etc, etc) - there's no rational reason to keep thinking depressing thoughts, so you just learn to control your thoughts better, so that you wouldn't ruminate on it pointlessly. It's not a solution, but it's the best you can do at this point.
I suggest learning meditation, so that you can learn to stop the scary and pointless thought patterns, and avoid upsetting yourself for no reason.
Find great books, fun hobbies, cool friends to have something fun to do instead of obsessing about depressing stuff.
Watch stand up comedy and great sitcoms, comedy is an amazing solution to this. Check out Louis CK and tv show Community. There's something incredibly beautiful about comedy, if things get bad it really saves my sanity, can't recommend it highly enough. If you are really down - watch a few episodes of Community, laugh your ass off, and it will get better =)
Also, I very much recommend you to read HPMOR. It has a lot of very interesting thoughts on the topic, it is just very bright and beautiful and interesting book. It won't solve the problem but I feel like it really helps.