Normally you don't "set-up" the Ethernet link, you just plug in the cable and it works!
The cable is dead.
That part of your PC where the cable connects - is dead (this can be a mobo socket or a PCI card socket).
If it's a PCI Ethernet card, is could be dead, check in device manager.
The socket on the router is dead.
WiFi is an alternative to the cable, thats why it works and the cable doesn't in your case. It is possible to have a PC connected via cable and another connected via WiFi - both will work without interfering with each other.