Problem -disappearance of NVIDIA nForce 10/100/1000 Mpbs Ethernet  

I have windown 7 o/s, Mother Board: ASUS M2N68-AM PLUS, with broadband internet connection. All of a sudden the internet got disconnected. On further checking the Network Adapter NVIDIA nForce 10/100/1000 Mpbs Ethernet has also got disappeared from the Device Manager. I have tried to update the drivers from the NVIDIA site and Windows update. Also tried restoring the system to a former date. Nothing works.

While trying to uninstall the old driver from C drive, I get the remark that "NAM" can not be uninstalled.

While trying to uninstall NVIDIA ForceWare Network Access Manager 1.00.7305, I get the remark that "Unable to Change directory to C:\Program files\NVIDIA Corporation\Network Access Manager\profile\Eth fail: Set Factory Default()"

I want to add that o/s is windows 7 Professional x 32 bits. The same modem is connected to my other computer with Windows xp and in it no problem of connection.