Visit the Realtek website on a working computer, download the "Auto Installation Program" for Windows 7 for your specific LAN/Wi-Fi model, and copy it over. Steps to Install Network Drivers Offline in Windows 7
Expand the section (or look under Other devices if the driver is missing completely, where it will appear with a yellow exclamation mark as an "Ethernet Controller" or "Network Controller"). network adapter driver windows 7 offline installer best
If you aren't sure what card you have, go to Device Manager, right-click the Network Controller > Properties > Details > Hardware IDs Visit the Realtek website on a working computer,