How are you connected - directly into a cable modem, or through a router? If the cables are physically in place, and you still get a “disconnected cable” error, it’s possibly a hardware problem with the device on the other end of the Ethernet cable from your computer, so that your computer no longer sees that it is plugged into a network device.
If you haven’t already, try unplugging any devices between your computer and the outside world (e.g. your cable modem and router if you have one) for two minutes, then plugging them back in and letting them power up. If that doesn’t work (and it couldn’t hurt to try to install new drivers for your network card, as you suggested, as well), see if you can borrow a different router or cable modem from somewhere and check whether your connection works with different hardware.
Thanks much for those excellent tips and suggestions.
I am going to see if I can borrow a cable from a friend, to rule out a network card issue.
Next to “connect to” in LAN connection properties is a “configure” button for the network card. When I click “configure” it says the device is enabled and working properly. So I imagine the problem is more likely the cable.
I don’t have a router, so don’t have to worry about disconnecting or restarting that.
Thanks again for your help!