Minecraft is blocked and I know it's not

Everytime I open up Minecraft, the play button always says "play offline". Whenever I login, I cannot join servers. But the worst thing is, when I logout of the my account and then try to log back in, it says, "Make sure you're online and Minecraft is not blocked". I know its not blocked because I checked my firewall. I definitely know I'm online since I can watch Youtube and do everything else that requires internet. But I can't manage to login the Minecraft launcher. Please Help!