i do partially agree with SO, but you can still have it show up and damaged, you can have done damage to the contacts in the connector in your pc (i do not know how you would do that, but i bought 2 switches with physically damaged port contacts, one still works with less than 100Mb/s the other no at all)
there is also the dual chips ethernet implementations, where you have the logic high level chip talking to the pc (and showing in the OS) and the physical interface chip, if the 2nd dies it will still show up but be dead and not work at all, both my old hp laptop boards have a nic pretty close to the cpu and a phy next to the ethernet port.