Turn ON, or reboot, you iBook with the 'Command S' keys pressed.
Once you are presented with the pre-1984 Mac release UNIX OS prompt, enter ...
fsck -f; reboot
... or ...
fsck -f; fsck -f; reboot
... and press the <return> key. Once the iBook checks or repairs the iBook file structurs, and reboots - does the 'Desktop' now appear?
If so, as an option - launch 'Disk Utility' ('/Applications/Utilities/' folder, if running 'Panther' - 10.3.x or 'Tiger' - 10.4.x), click on the 'First Aid' tab, click on your boot volume - in the left hand side list, and then click on the 'Repair Disk Permissions' button.
When the process completes, quit 'Disk Utility'.
An additional option (for peace of mind) - turn OFF, wait, turn ON - or just restart (reboot), your Mac and make sure it properly boots to the 'Desktop'.