During the vicious storm last saturday, i shut down my desktop prior to my electricity going in and out as i knew it would eventually happen. once the storm passed over, i reconnected the outlets and turned on the pc. no connection. the next day i called comcast since it still wasn't working. they finally made it out a couple hours ago and found the cable modem wasn't any good. awesome news right? switch up the modem and voiala (sp?), everything back to normal. not quite. the desktop doesn't recognize a connection. right now, i'm on that very connection with an ethernet cable in my laptop. i've looked at the device managers and nothing is out of whack. all i see is when i open up the network connections window is "network cable unplugged" even though that's not the case. currently, all 4 lights on the modem are either solid or blinking green with the laptop. as soon as i connect the cable to the desktop, the "enet" light goes dead. ugh! help! TIA.
your ethernet card could get fried. its happened before to me. the surge could have gone from the cable modem to the ethernet to your ethernet card.
do you have an ethernet port built in or is it a card? you can buy a ethernet card for cheap at frys and try it out to see if that was the problem. i wouldn't trust the device manager.
Check to see if when you hook the network cable to your ethernet port if any lights come on from the inside of the ethernet port. If not you've more then likely got a physical problem. Could be the network cable, could be the cable modem, could be your NIC. Start switching things out and see if anything makes the light come on. If that's not the case and your light is on then you can try checking the speed of your network connection. Make sure it is on auto detect and not hard coded. Good luck.
tinman is right, its a possibility it is the NIC. are you working with a router? if you are plugged into the modem/router in the very same port as the desktop was in and are getting a connection, you know your computer is the problem. Go buy a NIC, try it out.