HELP!!! My ibook is stuck on Starting Mac OS X page

So I hope im doing this write cause I have never posted anything!
I got an ibook off of ebay. I guess that was a mistake!! It was working fine for days but it asked if I wanted to do some updates so I let them download and restarted my computer. But now it gets stuck on the
Starting Mac OS X... page with the blue progress bar going across and when it gets all the way across it just stays there. I can move my mouse but nothing else. Someone please help me I dont have any discs either!!
Thanks

Trust you got thge Tiger DVD when you purchased the iBook. If so pop the DVD in and reboot holding down 'C' and go to Utilities>Disk Utility and Repair Disk.

Did you resatart the computer as you actually said? When Software Updates insrtall just let it do its things of installing, shutting down and rebooting. Sometimes it is quite a lengthy shut down and booting seems to take for ages. Did you interrupt the process by chance?

I dont have any Cd's it came with nothing, I just did what it said when it was done it said restart now or something and I did I left it shut off after that then my sister decided to turn it on for like 10 min. and shut it off not using shut down but by just pressing the power button thats pretty much it.