Q: PowerBook G4 displays question mark

Usually the appearance of a flashing folder with question mark on startup, indicates the

inability of the computer to find a working system; so that may mean the hard drive has

failed, or a cable, or perhaps other related hardware has made the previously installed

operating system unavailable to start and run the computer.

• How to choose a startup disk on your Mac - Apple Support

There are several related issues and general answers listed here:

http://guides.macrumors.com/Mac_doesn't_boot

If you have the install-restore DVD of the system installed, you could start the Mac from

the install disc #1 and see if you can use the Installer's version of Disk Utility check &

repair the hard drive; you can also choose the Startup disc (the computer or the DVD,

or an external drive) by use of Startup Manager to choose a bootable volume.

• Startup key combinations for Mac - Apple Support

• About the screens you see when your Mac starts up - Apple Support

Also, now that the newest OS X versions running in later model Macs use OS X Recovery

because their systems were not installed from DVD media, most later support articles do

not specify directly the old methods for dealing with the boot-up form install-restore discs.

One of the processes, along with boot-up from install DVD, is this install method:

http://www.thexlab.com/faqs/archiveinstall.html

Newer articles tend to omit the basics necessary to perform tasks in older configurations.

In any event...

Good luck & happy computing!