Internet connection problems?

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My wireless connection for my laptop is working, but when i go to use my home pc or my xbox live, the internet connection doesn't connect. Help!!
my 360 says- can't connect to Xbox LIVE. Select Test Connection to troubleshoot, or try recovering your profile....and when i test the connection it says to check the ethernet cable, to see if its connected properly.
and my computer says- no connection to the internet is currently available.
andd, all of this worked before, and i thought the ethernet cable just wasn't working, so i bought a new one and it still didn't work