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Just to verify something here, both wired and wireless connection doesn't work?
Now, my PC. It worked fine before ATT came and was messing with stuff to try and fix my internet. Now it can't find any network. When I hardwire it, the light next to the port doesn't even light up to recognize that it's hardwired. It has a wireless card and that's not picking up a network. It can't pick up a network at all.
Hare you tried a System Restore
? Restore it to a point where your computer was able to connect to the internet.
If System Restore didn't do the trick.....
While your PC is plugged in to one of the router's LAN or ethernet Port, please provide an ipconfig /all output. Here's a Tutorial