Windows has a built-in tool that can automatically search for and install drivers. This is a great first step if you're missing a driver for a specific device.
Before downloading drivers, you must know your exact hardware. The Asus K43S series has several sub-models, such as the K43SJ, K43SV, and K43SD. Each variant uses slightly different components.
Drivers act as the translator between your hardware and Windows. Without the correct versions, you might experience: K43SJ - Support - ASUS
Depending on your specific build, your laptop will require either the Atheros or Broadcom wireless driver. Check your Device Manager to identify the chip manufacturer before downloading.