- Start up from your Mac OS X Install DVD.
- From the Utilities menu, choose Reset Password....
- Reset the password for the affected account(s).
Do you have any installer DVD? Without it you cannot reset your password. If you are willing to try using the Terminal application, then give this a try:
How to change your username and/or password from the Terminal
1. Boot into single-user mode
2. At the prompt enter the following commands. Press RETURN after each:
mount -uw /
launchctl load /System/Library/LaunchDaemons/com.apple.DirectoryServices.plist
dscl . -passwd /Users/username password
Replace username with the targeted user and password with
the desired password.
This allows you to reset the password in single user mode without booting from the install media. The above tip is attributed to Satcomer.
You will need the username of the extant account. This will be the name of the /Users/user_name/ folder. In the Terminal you can get a directory listing with the command:
ls -al /Users