Since you didn't save the configuration, simply rebooting the unit will get you back to the previous configuration. I.E. the last one that was saved, and you will recover access.
If there's other configuration change that were not saved, they will be lost altogether.
It has already happened that a Cisco device worked for years with configuration update never saved, and then rebooted and.... troubles.
About seeing the configuration prior to reboot, there's no way I'm aware of.
Performing Password Recovery for the ASA 5500 Series Adaptive Security
Appliance
To recover passwords, perform the following steps:
Step 1 Connect to the security appliance console port according to the
"Accessing the Command-Line Interface" section on page 2-4.
Step 2 Power off the security appliance, and then power it on.
Step 3 During the startup messages, press the Escape key when prompted
to enter ROMMON.
Step 4 To set the security appliance to ignore the startup
configuration at reload, enter the following command:
rommon #1> confreg
The security appliance displays the current configuration register
value, and asks if you want to change the value:
Current Configuration Register: 0x00000011
Configuration Summary:
boot TFTP image, boot default image from Flash on netboot failure
Do you wish to change this configuration? y/n [n]:
Step 5 Record your current configuration register value (the number
that is similar to 0x00000011 in the example above,) so you can
restore it later.
Step 6 Enter Y to change the configuration and press Y.
The security appliance prompts you for new values.
Step 7 Accept the default values for all settings (which is N for all
settings by the way,) except for the "disable system configuration?"
value; at that prompt, enter Y.
Step 8 Reload the security appliance by entering the following
command:
rommon #2> boot
The security appliance loads a default configuration instead of the
startup configuration.
Step 9 Enter privileged EXEC mode by entering the following command:
hostname> enable
Step 10 When prompted for the password, press Return.
The password is blank.
Step 11 Load the startup configuration by entering the following
command:
hostname# copy startup-config running-config
Step 12 Enter global configuration mode by entering the following
command:
hostname# configure terminal
Step 13 Change the passwords in the configuration by entering the
following commands, as necessary. Note: the second word "password"
below is where you enter your actual password since the password
"password" is not a password at all.
hostname(config)# password password
hostname(config)# enable password password
hostname(config)# username name password password
Step 14 Change the configuration register to load the startup
configuration at the next reload by entering the following command:
hostname(config)# config-register value
Where value is the configuration register value you noted in Step 5
and 0x1 is the default configuration register. For more information
about the configuration register, see the Cisco Security Appliance
Command Reference.
Step 15 Save the new passwords to the startup configuration by
entering the following command:
hostname(config)# copy running-config startup-config
Step 16 You will need to repeat steps 4 through 8, except this time at
step seven press N for the "disable system configuration?"
