The Ethernet port is soldered directly to the logic board so it will have to be serviced by Apple and if this is the case AFAIK the logic board will need to be replaced. I assume you've tried resetting the SMC and P-RAM?
The Ethernet port is soldered right to the logic board and because of this it is VERY rare (though not unheard of) for an Ethernet port to be fried without doing other damage to the computer. Try resetting the power manager of the computer and swapping Ethernet cables. BTW - if anything did get fried, (but the computer is okay) it is more likely that the problem is upstream from the computer.