3DP Net is a free application which can find and install the latest network drivers for your PC.
The program comes with its own integrated driver library, which means you can use it even if you don't have an internet connection, or it's not working (which might be why you need a driver update in the first place).
Unlike many similar tools, there's no adware, no account registrations or anything else required. Just unpack the program, run it and wait for your adapters to be detected. A missing or outdated driver is highlighted, and you can launch the installer with a click.
Bonus tools include options to back up and restore your drivers, maybe useful if something goes wrong.
3DP Net is great for emergencies, restoring your network adapter even if you can't get online. But we wouldn't recommend using it on a day-to-day basis, as automated updating is likely to cause more problems than it solves.