Unable to start the launcher, "Make sure you are online..."

Hi. A few days ago I tried to connect to a minecraft server but then there was only "Unknown hostname" on all servers in my list. I tried to restart Minecraft and restart the computer but it did not work. Then I tested logging out of my account and logging in again and now I can't even log in to Minecraft. It just says "Make sure you are online and try again".

I've tried everything I come up with, I've even tried deleting Minecraft completely from my computer and then downloaded it again. I have seen people with similar problems and I have tried all solutions that i could find online.. I dont know what to do..