Greetings. I was deleting old wifi connections and accidentally deleted something. Now unable to turn on airport/wifi. It just shows up gray with an "x". And when I right click says. Wifi not configured. When attempt to configure in network preferences nothing happens. Under diagnostics it says wi-fi off. Click here to turn on - it never turns on. Have tried adding system configurations to desktop as recommended in an older post and rebooting. But didn't work. Any help greatly appreciated.