If you forget the password for your base station, Time Capsule, or AirPort network, you can reset the device and select a new password.
While the device is plugged in, use the tip of a pen to press and hold down the reset button for a few seconds. The device and network passwords are temporarily reset to “public.”
Open AirPort Utility, located in the Utilities folder in the Applications folder on a computer using Mac OS X, and in Start > All Programs > AirPort on a Windows computer.
Select the device you’ve reset, and then click Manual Setup. Enter the password if necessary. The default password is “public.”
Click AirPort in the toolbar, and then click Base Station.
Give the device a new password, and then click Update.
If you do not make your changes within five minutes after resetting, you must reset the device again.