Ibook g4 is loading with a blue screen that flash grey as well.

I just wouldwould like to see if someone could help me find a way to reboot my system it is I don't have the CD it was a gift . It flashes blue and grey I have done the resets as far as the pram and the NVRAM but to no avail if someone could really help me that would be greatly appreciated thank you.I don't have access to another computer only to A mobile phone with Internet thank you if some one can lead me in the right direction. I have tried as you do but it comes back can't access private files and other things and then it says fatal system send mail