MacBook Wifi dies, computer needs to be restarted I've been having a problem where my wifi dies frequently, and won't turn on again until the computer is restarted.  By "dies" I mean no wifi networks are visible - when you click the WIFI icon, it asks if you want to "Turn on Wifi" even though you never turned it off.  If you click "turn on wifi" nothing happens.  So I've been restarting the computer a lot. It's a 2013 Macbook Pro running OSX Yosemite, but the wifi problem existed before upgrading to Yosemite. I believe it's a hardware problem. 

Has anyone else had this issue, and if so, how did you resolve it?
Solution that avoids having to restart the computer:

Go to terminal and type

sudo ifconfig en0 down


And enter your password. This will cause the WIFI card to restart and (for me) the connection to be restored.