What I do when I have to trouble shoot a network is test some of the follow items

1) Check the ethernet cable/ use a new ethernet cable, one that is working, cat5 or cat5e (most often time, you have a faulty wire, or a wrong wire. It has to be one end male and one end female. It's easily identify by the mismatching color on both side of the connectors.

2) Check the network connectivity through the network properties. (Check the sent / receive) or you can try ping on CMD. If you have higher sent and very low receving, it's the router/ port or faulty wire. If you have low sent or no sent, and high receiving, then your network card might be broken.

3) Check the ethernet port on the router and on your PC end, it may be broken or lost connectivity. [it can seen easily by the blinking light [greenish yellow/orange -each represent different connection speed] Check your router setting, on the page of local area network guest, it should show ....several guest...including their mac address/IP check if your pc's ip/mac address is there.

4) Set up a simple network by directly connect the ethernet cable from your PC to another PC or laptop's ethernet cable and try to create a simple network.

5) go Start...type in device manager....check your network adapter....if it isn't properly install, it will have a ( ! ) and it's yellow