Q: iBook G4 has no OS. Freezes when booting from dvd

Not enough information is given in your post to determine much at this point. There may also

be hardware or other issues in relation to startup problems, so please supply missing details.

There is a possibility the OS X disc may be incorrect for use in the model iBook G4 you have.

Or there may be a hardware failure, a bad or worn component, disconnected cable inside, or

other reason for the unit to not work as expected. Cable damage or failed HDD? Perhaps.

Did you hold the C key down immediately after the startup chime, and continue to hold it

until there is indication of a desktop or finder in the display? Failure after several tries may

indicate hardware issues, including logic board or ATA/IDE controller, or hard disk drive.

Do you have the original grey label install-restore DVD media that shipped with that specific

computer model (build year, spec, etc) or a retail install DVD newer than the OS X which

would have been included with the unit when new? Do you have a second computer with

FireFire ports and a correct matching cable? You could try to see if the iBook G4 could be

started in Safe Boot mode, and the hard drive checked or tested, reformatted, etc by a

second computer which would see the Safe booted iBook G4 as an external drive...

Anyway, there isn't much here to go on, nor is there any way to tell what you may have tried

to troubleshoot the computer; which system discs you have, or processes you may've tried.

So a reply with some missing details is requested.

Until such time...

Good luck & happy computing!

The main problem with these products it the direct need to have the correct vintage

OS X install-restore system DVD discs of the exact build series as shipped with them.

Or have the later Retail install DVD media disc (newer than the factory included OS X)

to be able to start the computer and perform disk utility functions, and install a new OS.

How to use and troubleshoot FireWire target disk mode - Apple Support

With a working computer, and one that has FireWire ports, it is possible to start up one

(of two so equipped with FW ports) in Target Disk Mode and see if you can devise a

work-around by using the install DVDs  in a more closely associated vintage computer

via the other newer computer. Or, see if you could use a Utility such as Pacifist* and

learn how to use that install method to try to install parts without the Mac OS installer.

Older versions of Pacifist from CharlesSoft online should be available from maker site

and run in a demo version sufficiently to make use of them without much limitation, free.

http://www.charlessoft.com/pacifist_olderversions.html

*This is unlikely to work, but it may. However the resulting OS X may be inadequate to

actually to much good since the hardware changed several times across iBook builds.

https://en.wikipedia.org/wiki/IBook  (see iBook G4 snow, the dualUSB model)

You may be forced to wait until you locate a suitable install disc for use with that unit.

Depending on the vintage of the iBook G4, and its processor speed, the latest OS X

that can be run in it will vary; most later models with 867MHz or faster, may be able

to run Leopard 10.5 from retail install DVD. The disc will have adequate utilities in the

installer to set up and check the hard disk drive. Other problems can exist in these old

PowerPC G4/G3 portable Apple computers, such a logic board solder joint failures.

Not sure that I'm of much help here.

However good luck in this matter...!