Ethernet controller troubles

I'll start with a little background here:
Our cable modem used to run on an ethernet cable without any troubles. One day, however, it randomly stopped working. Unable to figure out why, I switched the connection to USB. I networked a laptop into the system using a wireless router without any troubles. The main PC, however, no longer has internet access; I need to connect the router to it using the same ethernet port that does not work.

When I tried to find out why, I noticed the ethernet controller was under "Other Devices" and had a ? icon to the left of it. I believe the driver was deleted accidentally by on of my brothers or friends, or even during a spyware scan.

How can I solve this problem?

 

you could reinstall the driver, so a newer version of the driver, that might work