ubuntu 12.04 internet stopped working

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http://askubuntu.com – My laptop was running smoothly until yesterday. Today, I can't connect to the internet at home anymore. I am only able to access the router, but no internet access. A have a Dell Latitude E6320 with ubuntu 12.04. At my job, I don't have any problems connecting this laptop both via wireless and ethernet. At home, if I try connecting it through Windows it does work fine. I even checked the MAC addess and it's OK. My other laptop, which also runs ubuntu, is not facing this problem. I have already tried to restart and downgrade network-manager package and its dependecies. Anyone can help me pleas (HowTos)