A power issue at a site (or someone at the site trying to help) fried the running config of an ASA 5505, so I used the steps found below to return the unit back to factory defaults and then restored a previous configuration into the unit.
type ‘enable’ to go to enable mode. Enter the password, or simply press enter if there is no password.
type ‘config t’
type ‘config factory-default’
type ‘reload save-config noconfirm’
The Cisco ASA has been reset to factory settings. DHCP is enabled on the cisco device, and it’s internal IP address is now 192.168.1.1!
If you had an enable password, you may need to enter that in the password box when you connect using ASDM, otherwise the default username and password are both blank.