My personal experience is to download software like the driver wizard directly on another computer with Internet access, and test to see if the driver is not online or the driver is broken 80% of the problem can be solved.
If not, it is necessary to distinguish between desktop and notebook desktop has the hands-on ability to dismantle the machine to see whether it is an independent network card, is to remove and replace the network card operation, not to the computer repair shop for testing and maintenance, notebook directly to the computer shop or after-sales maintenance.
These are personal views.