A couple days ago I got hit by a thunderstorm, when I checked my desktop my internet connection wasn't working. It's saying there's no ethernet cable connected. At the time my router wasn't working either. I've replaced the router and the wi-fi is working, but my PC still doesn't detect the ethernet cable. I've tried replacing the cable and uninstalling the drivers, but it still doesn't detect the cable.
If the router got fried, there's a chance the motherboard's Ethernet port also took a hit. Check with a known good Ethernet cable. If it's still not working with the new router, then it's a good bet the port is gone and an expansion card would be the way to go.