I use a laptop, and have only just been able to finally connect an ethernet cable to it. However, ethernet doesn't work on Linux, returning this "Cable Unplugged" message, whereas it does work on dual-booted Windows.
I tried running "lspci -v" to get a list of where my drivers were located, but I could not find any entry for "Ethernet controller," or something of the like. That being said, I'm assuming I just don't have an Ethernet driver?? and I was wondering how I get one :)
If it isn't showing up in lspci then it isn't currently attached to a PCI port. lspci will show all devices with or without a driver, known and unknown. You can try lsusb to see if it is attached internally to USB (very uncommon). It might also have a firmware level power saving disconnect feature that needs to be either disabled or managed by the OS in some way. It might also be showing up as a different device than you expect (also very uncommon) most cards will show as either Ethernet controller: or Network controller:.
Make and model of the laptop and any identification details from the ethernet device under windows would be helpful for diagnosis.