How do I face co-workers rejection?

First of all, English is not my first language, but I decided to ask for help in this community because I think I can get an objective advice about my problem, my country forums in others web sites are a joke and they're mostly harsh to other people asking for help.

Well, I'll try to explain a little my situation:

Two months ago I started to work at a new large international company, I'm working at an office surrounded by 30 other people and working directly with other 5 people. At the beginning, everything seemed fine, I was happy at that place, even I loved to go everyday, sit down in front of a computer and do my job, I had a "good" relationship with my co-workers or at least I used to believe that but then, everything changed.

It was Friday, lunchtime, everyone decided to hangout but nobody told me about it, they simply left the office and I stayed there like a fool, like a loser, nobody asked me if I wanted to go with them or if I was interested to hangout with them, just like that, I stayed there in front of my computer, without even a word from anybody.

I don't even know if I did or I said something wrong, for me, everything was right until that day or at least it seemed like that.

Obviously I feel rejected, because after that day, everyone hangout and enjoy the lunchtime but I haven't even been invited once, it's hard for me, because since I was a child it has been difficult to me establish good relationships with other people, I thought this time would be different, it would be a new beginning but it the same after all, I don't even know what's my problem and thanks to that I can't solve it or even modify my behaviour.

I'm looking for a sincere advice, not for a critic or sarcastic comments, for that I have a lot of people out of this website, I need help because after that situation I feel anxious and nervous working with all of those fake people.

Maybe Im taking this situation very personal, but I cant avoid it, its hard to me, I feel sad and Fridays are the worst days for me, I think this affect me a lot because it happened before, friends have betrayed me and my confidence is a disaster, I faced this new job with a new attitude, I've tried to be positive everyday, show a smile to everyone, be assertive in my discussions, I dont know whats wrong with me, because at the end nothing has worked.

Some people have told me before that I dont show enough interest in other people and that is my main problem, but I dont do it consciously, I like to meet new people but I dont like to ask a lot of questions and sometimes I dont even know what should I ask to someone because I dont feel the necessity to know them a lot, I know this is a problem by itself but I dont know how and why should I change that.

I hope you can help me people, maybe youve faced this kind of problem and youve been able to find a solution.

Thanks for your time.