No Supported WiFi Adapters available in your

My WiFi wireless system has been working perfectly. But just the today, it has stopped getting me access to internet via the usual netgear router I have been using. The WiFi icon on the task/tool bar at the bottom right of my computer is completely white, with a red X across it. Before now, when the wireless was working, it was solid green. When I put the cursor on it, it reads "No supported WiFi adapters available in your system. However, when I connect the computer with a cable, the internet comes on.

Please help me to restore the WiFi wireless network/internet connection.