NEW HARD DRIVE EMPTY ETHERNET

Hello,

I had a very severe virus and a bad/old hard drive. i completely replaced the hard drive with a new one and windows downloaded fine however it is not recognizing my high speed internet which is provided by COX. it states no Ethernet connection what have i done wrong? in order to download something for this i would need internet correct? but if i cant get online then how can i fix? is there a disc i need to purchase? can someone please give me some advice i can use and understand to remedy this!!! i have to use an old computer with linux programmed in it and i hate it! cant load anything into this computer or i would do so but the hard drives are different and the door doesnt open to completely wipe out linux and add my windows....HELP!!!!!!!!