What if there is no network adapter in the WIN7 system Device Manager?
First, the network card driver problem
Installation drive method: can be based on their own network card models to search the latest drive online, if you do not know the model of their own network card, or find the appropriate network driver. Can download the installation drive life, and then press a key to handle automatic installation.
Second, the network card hardware problems
If it is the problem of the hardware of the network card, we must buy a new network card, if it is a stand-alone video card, you can replace it directly. If your computer is an integrated video card needs to be in the BIOS to disable the original NIC, and then install a separate video card. The concrete operation see below figure:
After entering the BIOS interface, enter the integrated peripherals option shown in the diagram, and change the onboard LAN device inside to disabled.