My MacBook suddenly decided it didn’t have an Airport card, reporting the error “No Airport hardware found”.

I fixed it by doing an SMC reset:

1. If the computer is on, turn it off.
2. Disconnect the AC Adapter and remove the computer’s battery.
3. Press and hold down the power button for 5 seconds and then release the button.
4. Reconnect the battery and AC Adapter.
5. Press the Power button to restart the computer.

Hat tip: Bruce Snyder

UPDATE: This fix also worked for repairing a “Bluetooth: not available” error. It may have helped repair a problem I’ve been having lately with the WiFi dropping in and out.