I do not know much about Ibooks, is the disk inside an IDE disk.
If so and you have a second computer then you could try the following, which I find works with PCs.
1. Take the disk out of the computer
2. Place the disk in one of those boxes which allow any lap top hard drive to be used as a portable USB disk.
3. Then plug in the USB disk, and copy the files off the disk onto another disk.
Even if the disk is so bad that you can not boot off it, you might still be able to get some stuff off the disk. A lot will depend on what went wrong with the disk.
_________________
Health is a state of physical, mental and social wellbeing and not merely the absence of disease or infirmity
I am not a jigsaw, I am a free man !
Diagnosed under the DSM5 rules with autism spectrum disorder, under DSM4 psychologist said would have been AS (299.80) but I suspect that I am somewhere between 299.80 and 299.00 (Autism) under DSM4.