It's weird that I have this problem just in Ubuntu not in windows.
I can't log in to gmail in Ubuntu at home (the specific ISP). But I can log in to gmail in Ubuntu (the same laptop) at the office. I don't have any problem with gmail in windows at home or office, it just happen in Ubuntu at home.
I'm really curious what windows has that Ubuntu hasn't got? I tried both 13.10 and 14.04.
Nothing happenes after entering my username, password and verification.
EDIT: I disabled the 2 step verification. It doesn't have any effect on this problem.
EDIT2: I can visit other sites. my problem is just with gmail. and i can log in using gmail in sites like askubuntu.com