It won't work if it's no good.
So, what willy posted:
If ya know the cable is good...
If ya know the connection is good....
If ya know the drivers have been set up for the NIC properly...
... then if it don't work the NIC is probably dead. If you replace it with a good one and still no network... it probably is NOT the NIC.
How's that? Help?
Cheers
Mick