i have a dell Latitude D600 laptop
i cant go on the internet or use the internal NIC card and its really bugging me
Even Dell Quick set Application cant turn ON and OFF the NIC

i go to power management and it says that the card is off, but i dont know how to turn it on
Pls Any comment

did you try device manager ,network adapter and see if its disable there ,if so enable it and see what happens .
device manger= right click on mycomputer /properties/hardware /device manager

If visible in Device Manager, but showing a yellow triangle, is likely a driver issue... if recently applied updates, or especially Service Pack, may have a compatibility issue. In this case, go to manufacturer's website (likely Intel) and download latest driver stack and install.

If not visible in Device Manger is likely a hardware issue...either device has come loose or blown. If confident enough, oper case and check to see if device has come loose - otherwise take in for service tech to look over.