I received a free Cisco Aironet 1200 and tried to restore it using the mode button but it was disabled and no one knows the password for the WAP's interface. Any ideas how I could get it reset?
You'll probably need to attach a serial cable to the console port. Getting console on cisco devices can be a real pain. You basically want the baby-blue RJ45-DB9 cables that comes with real routers.
Try following the directions in the link below for the Aironet 350 (which lacks a mode button):
Briefly, you want to interrupt the boot process with ESC, then
flash_init to load the flash memory, and then rename the config.txt to something else, and reset. This should restore factory defaults.
To return all access point settings to the factory defaults including password you need to use the MODE button.
Disconnect the power and press and hold the MODE button while you reconnect power to the access point. You need to hold the MODE button until the ethernet LED turns amber (approximately 2 to 3 seconds), then release the button.
Then you can connect with cisco/cisco via serial console or web gui.