I have 775twins hdtv motherboard but in the manufacturer site there are only drivers for windows xp, and my computer is missing the Ethernet drivers what can I do
There are no official Windows 7 drivers for that ethernet chipset. There are some 3rd party drivers you can find out on the internet, but I avoid those like the plague. Your best bet would be to buy a new ethernet card. Ethernet cards are cheap and you can get one that is guaranteed to work with Windows 7 and 8.