When troubleshooting a network card that is not being detected by Windows, the following steps should be taken:
1. Check the device manager to ensure that the network card is listed.
2. Ensure that the network card is properly installed in the computer and that all necessary drivers are installed.
3. Check for any loose cables or connectors that may have come loose during installation or use.
4. Check the BIOS settings to verify that the network card is enabled.
5. Ensure that the latest version of the driver for the network card is installed.
6. Try disabling and then re-enabling the network card in the device manager.
7. Try uninstalling and then reinstalling the network card and its associated driver.
8. If the network card is using an external power adapter, make sure that the power adapter is connected properly and that it is plugged into a functional wall outlet.
9. If using a router, check to make sure that the router is functioning properly and that the computers are properly connected to it.
10. Check the firewall settings to make sure they are not blocking the connection.
11. Check the system event log to see if there are any clues as to what may be causing the issue.
12. Boot into Safe Mode with Networking and see if the device is detected.
13. Verify that the network card is compatible with your operating system.
14. Try updating the firmware on the network card.
15. If none of the above steps work, try replacing the network card with another known good card.
16. Check the online support forums for solutions or ask for help from experienced users and technicians.
17. Consider taking the computer to a professional for diagnosis and repair.