Network Cable unplugged

Your question is vague but several reasons can exists. heres a list you could try.
the fact that it shows nC unplugged means that you most likely don't have a driver problem and u can rest easy. so
1. check config is IP assignment by DHCP or is it static.
2. sure your using an ok cable make sure it ain't a cross over
3.does the network point work??
4. are you running on battery? some laptops switch of the NIC on battery to save power

hope one of these help

or check the port at the other side?

It usually means a physical problem - swap the network cable. If that does not work plug it directly to the switch or into another patch port on the wall.

Maybe the cable itself is bad or the RJ-45 end connector is damaged in some way. Try another cable and plug the other end into a switch or hub that you know works. Another thing to check is to make sure that your speed/duplex settings match on both the NIC and the switch you are connecting to.

I suspect the RTL9168/8111 itself or some setting with it to be to blame.
I have the same onboard nic and it works fine with my good old Surecom EP-808SX Switch (10/100) but as soon as I connect it to a Gigabit Switch (tried 3 different kinds) it says "Network cable unplugged".
No it is not the cable, checked and tried multiple cables they are all CAT5e and work with Gigabit on other computers...