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
You may have a faulty network card....or a corrupted driver....not sure which. If all fails by today, return the network card to the store where you purchase it and get a replacement
If you have two computers in the network, try to ping the other computer's IP using the computer that have ethernet card issue. Try the same thing with the computer with internet connect. You know the other computer's IP address, now try to ping each other. Go CMD and type "Ping xxx.xxx.xxx.xx" <- without the quote. If there is a connect between the network you will get a response. Example how many bytes are sent, time it took to send it and TTL of the packet that was sent.
Oh and its not a faulty card. Had it at my friends house and didnt have any problems at all. Though he has charter which is a different ISP but still...
Media state: Media disconnected
Connection-specific DNS Suffix:
Description: Microsoft ISATAP Adapter
Physical Adress: 00-00-00-00-00-00-00-e0
DHCP Enabled : No
Autoconfiguration Enables: Yes
Tunnel adapter local area connection* 9:
Media State : Media Disonnected
Connection-specific DNs Suffix:
Description: Microsoft 6to4 Adapter
Physical Adress: 00-00-00-00-00-00-00-e0
DHCP Enables : No
Autoconfoguration Enabled : Yes
this used to happen to me allot back in high school but that was mostly a windows xp thing.. i could only ever fix it by doing a computer restore from a point that i knew worked (i made a restore point) try doing a system restore back to a time when you know it worked.