I kicked out windows 7 from my pc , and installed Linux Mint 14 cinnamon. I had connected to a wireless network. After I turned the laptop's WiFi off , it wouldn't go on again. I restarted my pc , reinstalled Linux Mint , but the same problem after turning off the WiFi. Later read somewhere that this happens because Linux kernel soft blocks WiFi when turned off. So , in order to use it again , you must unblock it. This can be done by typing the following in your terminal.
$ sudo rfkill unblock all
and the WiFi is back !!!