Airport won't turn on

Hey Sarah,

I found an article that looks like it matches the issue you're experiencing here:

Mac OS X 10.5.5: Can't turn AirPort on after turning it off and restarting

http://support.apple.com/kb/TS2416

There are two troubleshooting routes depending on whether or not you have an Ethernet cable handy, I'll paste both below:

If you can connect to the Internet via an Ethernet cableNote: You can also use these steps if you have a MacBook Air and an Apple USB Ethernet Adapter.

1. Connect an Ethernet cable to your Mac. The cable should also be connected to a router or broadband modem that provides Internet access.
2. Download and install AirPort Extreme Update 2008-004.
3. Once installed, turn AirPort back on via the AirPort menu or in the Network pane of System Preferences. You do not need to complete the following steps.
   

If you have a MacBook Air without an Apple USB Ethernet Adapter, or do not have access to a wired Ethernet connection

1. From the Apple menu, choose System Preferences.
2. From the View menu, choose Network.
3. In the list of available network connections, select AirPort.
4. Click the "-" button to remove the AirPort interface.
5. Click the "+" button and add an AirPort interface.
6. Click Apply.
7. Turn AirPort back on via the AirPort menu, or in the Network pane of System Preferences.
8. Download and install AirPort Extreme Update 2008-004.

Note: Removing the AirPort interface resets your preferred AirPort networks. You will need to add preferred networks again.

Hope that helps,

David