wireless - Wi-Fi disabled in Ubuntu 14.04

I've seen this question already asked and tried suggested solutions but none of them seem to work. I've had the wifi become disabled previously but rebooting the system usually worked. This is not working now. When I run rfkill list all, I get this:

0: phy0: Wireless LAN
    Soft blocked: no
    Hard blocked: yes

How do I undo the hard block? I'm using a Dell Inspiron N7010 with an Intel Centrino N-6200 card.

Edit: Output of lspci -knn | grep Net -A2 is as follows:

Inspiron-N7010:~$ lspci -knn | grep Net -A2
03:00.0 Network controller [0280]: Intel Corporation Centrino Advanced-N 6200 [8086:422c] (rev 35)
Subsystem: Intel Corporation Centrino Advanced-N 6200 2x2 AGN [8086:1301]
Kernel driver in use: iwlwifi