Q: lost my password ibook g4 mac OSX?

If you have the OS X installer discs for the version running in the computer,

you could start the computer from the install disc #1 and carefully get past

the setup since you don't want a new installation, and use the Disk Utility

which exists in that startup media.

• Reset a Lost Password in Mac OS X with a Boot Disk:

http://osxdaily.com/2010/02/21/reset-a-lost-password-in-mac-os-x/

This should be your first and perhaps only option. A retail install system

disc, if the Mac is running a later version than originally shipped, can do.

Generally avoid installers from other build model Macs on grey label disc.

• Five Ways to Reset a Lost Administrator Password*:

http://tidbits.com/article/14437

{*see comments section in tidbits article for 'shortcut single-user' command}

...A more extensive on this topic exists, for newer & older Macs with other

means that may not work in vintage or obsolete hardware... Note the one

where you could use Command-line, which is rather lengthy and detailed:

• Forgot Mac Password? How to Reset your Mac Password with or without CD:

http://osxdaily.com/2010/08/10/forgot-mac-password-how-to-reset-mac-password/

The best one for older Macs is to use the boot install disc for the computer;

since old computers cannot use OS X Recovery & other fancy stuff anyway.

Better to remember the password, or use a sticky on the Mac's display LOL!

The command line can be  helpful if you really cannot find a correct install disc.

Good luck in this matter!