Chosen Solution

forgot my password and no install disc what can i do to change password

This is one off many ways, to avoid having to recall from memory as Chris Green has done, I collect different ways into a file for quick and easy reference:

  1. Boot into single user mode (press Command-S at power on)
  2. Type fsck -fy
  3. Type mount -uw /
  4. Type launchctl load /System/Library/LaunchDaemons/com.apple.DirectoryServices.plist
  5. Type dscl . -passwd /Users/username password, replacing username with the targeted user and password with the desired password.
  6. Reboot

You could reset the operating system but this will delete any user accounts (but save all the data, unless you have filevault enabled, since it encrypts your data with your password, but new accounts can be created, and if you remember your password later, you can recover the encrypted data) If you can boot into single-user-mode, type these 3 commands, and than reboot the machine, and it will take you to initial setup, though all the old files will be on the disk somewhere: Boot into single user mode by holding “Command”+“S” after the chime until you see a prompt. Type These Commands(In This Order): “fsck -y” “mount -uw” “var /rm/com.applesetupdone” this 3rd one might be wrong, since i am reciting it from memory, but try it anyway. Good Luck