The latest LAN related firmware (that Intel wants you to run with the hardware on your board) is included in the latest BIOS update for your board (which is freely downloadable from Intels support section website under discontinued boards). What caused your LAN to disappear in the first place? The last time I saw such behaviour (on a different motherboard) it was as a result of lightening toasting this part of the mobo after hitting the phone lines of the victims setup and getting through their router. If you don't already have effective surge protection (including for your phone/dsl line) you should get some. You MAY need to install a 3rd party NIC into a spare slot if your onboard LAN is gone for good and diable that part of your hardware in the BIOS setup options).