Unable to connect to the authentication service.

Hello! Every time I sign in it show me "Unable to connect to the authentication service" and i cant even visit the auth.riotgames.com on website .My computer broke down when I was playing league of legends a month ago. When its fixed, it wont log in. I think I'm banned from visiting the authentication, I try to close the firewall ,change some network setting and use hextech repair tool .But it didn't make sense . I need help.