|Did you change anything in the settings? Is it set to automatically acquire and ip address in the network connection. When you right click the network connection and press status and go to support what is your ip? |
By the way your network connection can be found at start > settings > network connections if you didn't know that already.
Obtaining an ip address automatically can be checked by right clicking the network connection and pressing properties then going down to tcp/ip clicking on it and pressing the properties button.
Since most virus' like you to have internet access so it can spread itself, I expect this is not a virus.
I would think it is a hardware issue. Either you took the ethernet cable to your bro's house when you went and it is bad or your network card is bad. Do you have a network card integrated into the motherboard or is it pci. You can find pci cards on sale sometimes for under $10. If the one you have now is pci you would just uninstall it in the device manager then turn off the computer, take it out then put in the new one. It just plugs into the slot and goes to the opening in the back of the computer on the bottom. When you turn on the computer you follow the instructions that came with the card.
If you have an integrated card you just disable it in the device manager then install the new one.
I just noticed you have a Dell. If it is under warrantee you call them and make them fix it.