Can't connect to internet. Trouble shooter asks "plug an ethernet cable into this computer." WHAT?

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I have windows 8 and so does my brother. Also my mom has windows 7. The rest of my family including my phone all the other phones in my house their computers and my brothers kindle all have connection. It said an ethernet cable is broken which is bs. Also when I try to open the hp system recovery it never opens. I'm trying to stay up to fate with my virus protecting but I can't without internet... Charter has recently rebooted my router and stuff and it should be all good. I think something may be wrong with my computer internally. I've tried plugging the cable into my computer and then it doesn't even fix anything. I have limited internet. Which still allows me to do nothing. I need someone we'll educated to help me out. I hope I've gave you enough information. Thanks for anything.