Apple 12" ibook g4/1.33ghz won't turn on

I found this page at apple support about your problem, it seems to have helped a lot for many people. Apple Support

If it turns on and you get a gray or blue screen with an Apple symbol and a rotating circle - your hard drive it shot and you need to get a new one.

Did you try rebooting while pressing the trackpad? This should give you a list of available hard-disks.... If it doesn't... Then it should be a hard-disk problem...

Blinking ? mark folder means that your OS can't be found. Take out your RAM underneath the keyboard and re-insert and try again. Nothing? Install a different new RAM chip and try again. Nothing? Install your disc 1 install disc, power down, wait a few seconds, now press the power button to turn on, now press and hold the option button, until your disc 1 shows up, select it, and bring your pointer to the right arrow on the screen and press enter. Now your booting from the disc 1. Go to disc utility folder at the top of the screen and select your hard drive and then select repair disc permissions. Then shut down and reboot when finished. Nothing? Your hard drive is fu.k.d-Try re-installing the OS. Nothing? Your hard drive is really fu.k.d-You need a new hard drive. Installing a new hard drive in the iBook is a *****. You may want to pay someone to install a hard drive or you can just get a new laptop.

You need a new hard drive.
If you have another mac you can see if plugging it in in firewire mode helps. If it connects try repairing the disk permissions. If this is all Greek to you email me i can walk you through.

Check the hard disk, it's probably dying.

have you tried putting the mouse icon to the bottom of the screen? that is a setting on macs it takes a few seconds to show the icons. if that doesnt work try going into settings and putting it back to default or factory reset of settings.

Sounds like your hard drive is failing.
Try booting while holding down the shift key that will put you into safe mode and run some diagnostics at the same time.
If you have the discs that came with the laptop try booting from them while holding down the D key. That will bring up AHT a built in test for your mac. You can use it to test and repair some of the disc problems you are describing.

time to get a new laptop

Try starting from the system disks and running disk utility. See if it finds any problems on your drive. There may be some type of problem causing you to stall on startup. If so, click the option to repair the drive.