Before replacing any component three things should always be done first, confirm that the component/s needs to be replaced, if yes, establish what caused the component to fail and was anything else affected, you then need to check if it is safe to replace any component, seen it many a time where someone has swapped in a new component only for the new part to suffer the same fate.
What makes you think that lightening took out the Ethernet and NIC device.
What has been done troubleshooting wise.
What operating system are you running and when was it installed.
Fwiw, lightening is not selective and it is most unlikely that your communication devices have been singled out by any lightening strike, a 100% dead PC would be more likely.