Recently I had a problem. After having my 4yo son fiddle with my laptop for a few hours, my laptop locked itslef with no wireless. Pressing the WiFi button didn’t help at all. After some hours of researching I found a solution. Here is it below. Hope it saves a few people some hours of troubleshooting:
user@linuxtoolz ~ $ sudo rfkill list [sudo] password for user: 0: hci0: Bluetooth Soft blocked: no Hard blocked: no 1: hp-wifi: Wireless LAN Soft blocked: yes Hard blocked: yes 2: phy0: Wireless LAN Soft blocked: yes Hard blocked: yes
You will notice quote a few networks above. hp-wifi and phy0 are for your WiFi card. Soft block is very simple to take off. Just issue the following command and soft block will be off on all interfaces:
user@linuxtoolz ~ $ sudo rfkill unblock all
Now the problems start with the hard block. Pressing the unblock button on the laptop switched the hp-wifi hard block on and off but the phy0 stayed hard blocked (Hard Block: yes). Here is what I found out:
Pressing the WiFi button in linux swapped hp-wifi hard block on and off. If I reboot the machine and press the WiFi button on the laptop ONCE sometime before linux boots (took me 3 tries to get the timing right – needs to be somewhere between the BIOS and OS boot… hard to say) – then the phy0 hard block will go off! I can use my laptop WiFi again!
Hope this helps all you troubled people! 
Excellent post! Saved me hours of searching!
Was looking for a solution for days! Thank you, this worked like a charm.