Network has vanished!!

I bought a new uATX motherboard, a BIOSTAR G31D-M7 recently to replace my brother's old dying setup. This morning, his network connection vanished, and he has no way to connect to the internet. I check device manager and the network adapter disappeared from there as well. When I go to view, display hidden devices, the network adapters link shows itself, but there is no REALTEK adapter listed. This happened to his last motherboard as well, and I'm starting to think it has something to do with his HDD because that's the only part that's the same from the last build. Is there anything I can do to get his built in ethernet port to be re listed? I'm going to need the internet for a few weeks from that computer... Thanks.

OK I seemed to have fixed my own problem. I restored to a point when the network card was working... I still wonder though what cause this to happen... weird.