My PC says that Ethernet cable not connected...but i don't use Ethernet cable...

The last night i started My PC and it has no wifi conection. The diagnóstic says "the ethernet cable is not conected"... But i don't use that thing. Help! My PC has free service but it's too far (If there’s no solution, I’ll take it. I’m asking because maybe it’s something simple and it can be fixed)

Sorry for my English