How to Enable an Ethernet LAN Controller
Your computer's Ethernet adapter allows you to connect your computer to another computer or network device via an Ethernet cable. By default, the Ethernet adapter should already be enabled on your computer. If the Windows operating system is reporting that your controller is disabled, you can re-enable the device through the Network Connections or Device Manager window. If the device is not listed in Windows at all, you will need to enable the Ethernet controller from within your computer's BIOS.
Enable through Windows
Click the Windows "Start" button. Type "Network Connections" in the "Start" Search box and press your "Enter" key. This opens a new window.
Right-click your LAN adapter in the window that appears and click "Enable." Continue reading if you are unable to find your adapter in this window.
Click the Windows "Start" button again. Type "Device Manager" in the Search field and press the "Enter" key.
Double-click "Network Adapters" to expand a list of your Ethernet adapters. Right-click your adapter and click "Enable." Continue reading if you are unable to locate your adapter.
Enable through BIOS
Restart your computer. Pay close attention to the first screen that displays as the computer is restarting. Look for the message that instructs you to press a specific key to enter the setup menu.
Press the indicated key quickly and repeatedly to enter your computer's BIOS. Once in the BIOS, you can use the arrow keys on your keyboard to navigate through the available options.
Find "Integrated Peripherals," "Onboard Devices," "OnChip PCI Devices," or similar text. Press the "Enter" key to access the menu. Depending on the type and year of your BIOS, the exact menu text will vary. Generally, you should find something that indicates the settings are related to your on-board integrated peripherals.
Find and select "Integrated LAN," "Onboard Ethernet," or similar text. Use the left and right arrow keys to cycle through the available options. In most cases, these are either "Enabled" or "Disabled."
Press the "F10" keyboard key. This should display a dialog asking if you would like to save your settings and exit the BIOS. Press the "Y" keyboard button to confirm. This causes the computer to reboot. Windows should now automatically detect and use your Ethernet controller.