That's not a problem with Internet. It would be a problem with your home network - if you had one - also.
If google the error message you gave with https://www.google.com/search?q="cable+adapter+network+unknown" google finds nothing. So either you have a very unique problem, or you get another error message than you tell here or it's a bad translation into English. That makes it nearly impossible for anybody here to help. Can you find it yourself with google?
And can you tell what changed since it last worked? I don't assume it's a totally new PC right from the shop now. And I don't assume either that it never worked on this PC. So something must have changed to cause this (either hardware, software or settings).
In my nework and sharing systen is writen theat is cable adapter network unkown and access denied. And when i open the change adapter settings theat folder is empty.