I use Firefox and Chrome. When Mozilla can't access that site I go to Chrome then it works. When that problem happens I go back to Mozilla and vice versa. On IE9 there is no hope at all it doesn't open. I googled this trouble and many people faced this problem.
I got this funny story from a person facing this problem: On his computer he can't open facebook at all and he thought that his account has some troubles. After a week of facing this problem, he went to a foreign and he went to the internet cafe. Surprisingly, his account opened without any trouble
So I guess there is problem with the PC itself. I don't want to format again because I installed a lot of big softwares. I hope the info I gave is better guys. Thanks!