So, I guess this is me partly coming to this community for help, and partly creating an open discussion. Recently I had someone close to me in my family pass away, ever since I cant get the concept of death out of my head. As far as religious views I'm not really sure what I believe in but I fear that when we die that that's it, that it'd be instant oblivion, that I would completely cease to be. It's just this all consuming fear that's looming over me lately, so I'd like to hear from you guys about it, what are your views? How do you deal with it? I'm just looking for help about this, truth be told I'm kinda desperate....

I know this is probably going to sound really stupid, but I get into super bad bouts of depression where I contemplate things like this all the time, and the only cure is forgetting about thinking about it. It takes a lot, but I have to immerse myself in something else. Otherwise, I end up in a really awesome mood. It's not common though... Just try to distract yourself, this IS normal.

I agree with Slacker.Thinking too much about your existence after death would really make you cower in fear. The reason for this is because we don't really know what happens next after we die. My suggestion is for you to think more about what you can still do, while you're still alive. Something like what you can leave behind that might help someone else. When you find something that can make your time worthwhile, it can help. Never mind death distract yourself with things that can make you feel satisfied. To repeat what Slacker said "This is normal".

In my opinion, just as it was said in the previous answers, there is no need to ask yourself what the "dead state" is.
There are multiple reasons :
If there is nothing, existing is an experience, but also not existing may be another.
If there is some kind of afterlife, we can't even try to imaginate it, because we think with our brain, and without a flesh and blood body you can't do it. The only thing that can remain is the soul. And we are far away from understanding this concept.
No really, you should probably try to forget it.

just in case you can't stop thinking about it (although that would definitely be a good idea):
just up front i want to say that it is extremely hard to depress me so i can remove this comment if it bothers anyone.
i don't believe in souls. my view is that humans are pretty much very complicated machines that (who) are programmed for survival. while trying to make survival easier and easier, we have created technology that exceeds our evolution speed (this is why we have problems like eating too much sugar; it's an important recourse, but our bodies haven't evolved to know when to stop eating it). this is what we call "luxuries" (pretty much anything that you have, but that is not a bare minimum for survival). eventually our bodies wear out to the point of not being able to function: death. it's really not that big a deal. This next part may be offensive to some religions. (it's not meant to be. this is just my view on the subject.) i just can't really imagine every single person that has ever died all in one place, living (not exactly) there for the rest of forever. if you just consider the whole thing very casual, it might help. my solution is just to go with it. because it's simpler. and there's no end goal in any case. so might as well. it works for me.
and no, this doesn't count as oblivion. that would mean you could consciously experience oblivion.
again please tell me if i should remove this comment. i get that lots of people probably disagree with me on this.

This is one of the oldest questions asked by man. Quite possibly the biggest question to ever face mankind. I have learned to be comfortable with not having an answer.

Even if I decided what to believe, I could only BELIEVE I was right.

Things like loosing a loved one can shatter the world around us, and remind us of our own mortality. It's up to you, afterlife or not, to leave a mark on this world. Spend your time here creating something that lives on.

Got the same problem since I was 11. Feels shit, but you don't really progress in life thinking about that. It can't be helped. Make the most of what you can now.

If you're looking for a remedy, maybe we'll still live to see transhumanism at it's best. Bionic limbs and body parts. Breakthroughts in biotechnology and shit like that.

Here's an interesting one, I've been thinking about:
Let's say there's a technology with which you can replace a part of the brain. Sort of like a machine brain part, tailor made for the piece they cut out of yours.
If we would cut your brain out, and put a machine inside instead, that would surely not be you anymore, since your brain has been removed.
But if I only cut a part of your brain out, and then put the "replacement" piece in, you would probably feel like you've fallen asleep or unconscious or partly unconscious for a small period and then feel like yourself again. For example we cut the part which is responsible for your linguistic skills and then replace it. So you couldn't speak for a while then you could again. We would do this slowly with all the other parts. Would you die then? Would you be fully replaced? Is there a place in your brain I could cut out that is responsible for you being alive? Or would you live on for the rest of the machine brain's lifetime? What makes you alive actually? I mean, you, your "soul" and intellect is the mass of structured information stored by your brain. Everything you are has evolved out of stimulus from the environment, information coming from outside, being stored inside of your brain. So would there be a way to preserve that, even though we remove the brain from the equation? Or would that be a copy of you? Another instance of you, you as in the same information, but not you as in not that specimen of information? These are the questions that pop up for me, and that's how I kind of look at it too.
That death would probably feel like the last time you go to slumber.

I had a precious family member pass away too. I dealt with death in this way: Instead of the regular "don't think about it" I tried coming up with solutions, so I came up with your same question: "What happens when we die?" I think people die and that's it, there's nothing you can do. But I'm really keen on thinking that dead people are still alive on your memories. Each moment you spent with them was a precious one, and that's all that matters. The only thing that changes is that the "physical body" is dead, but your memories aren't. Wish you the best of the luck dealing with this.

“Never tell a child,” said George Macdonald, ‘you have a soul. Teach him, you are a soul; you have a body.’ As we learn to think of things always in this order, that the body is but the temporary clothing of the soul, our views of death and the unbefittingness of customary mourning will approximate to those of Friends of earlier generations.”