Ubuntu loves messing up!
This evening, when I reached my home and booted up my laptop I could not simply enable wifi! The option was disabled.
Last time I faced same problem, I had switched to windows 7 to search for solutions, but this time I had no other operating system installed in my machine. Also last time, I had to do nothing to solve this problem, just switching OS had automatically solved the problem. But this time, I really had to find solution. With a bit of searching, here is how my problem was solved.
# step 1: run rfkill list all $ rfkill list all 0: phy0: Wireless LAN Soft blocked: yes Hard blocked: no 1: hci0: Bluetooth Soft blocked: no Hard blocked: no # step 2: ublock the wireless LAN $ rfkill unblock 0
Just running 2 commands solved the problem. Hope this will be helpful to you too.