My Optiplex desktop is connected to my router via an ethernet cable and has been working fine. We had a very close lightning strike while I was using my computer, and at that exact moment my Internet stopped working.  My cable modem and router are working and my laptop (wirelessly connect to router wi-fi) works fine and accesses the internet ok. My desktop computer is working, except that it thinks there is no ethernet cable connected.  I have tested with a different cable; it is not a cable problem. And it is not a router problem because if I connect the laptop to the router with an ethernet cable, that connection works.

So I am thinking this is narrowed down to the ethernet port on my desktop.

When I go to the control panel on my desktop and look at "Network and Sharing / Change Adapter Settings" it says the Local Area Connection is disabled.  I right click on that, select "Enable", click "yes" to allow the Network Connections App to make changes to my device,   That gets me to a popup window that says "Enabling" and then "Enabled".  But nothing changes, still no internet connected.  If I click "diagnose" it gives the message "Plug an ethernet cable into the adapter "Local Area Connection".

The only other clue is that there is a steady yellow light where the ethernet cable plugs into the desktop computer. I don't know what the means?  I am thinking that for some reason, the internet card itself is not seeing that the cable is connected.  Any suggestions or insights would be appreciated.  Thanks in advance.