Powerbook wont boot up

I have a g4 ti and i was trying to reinstall 10.5 on it. now when i go to restart it it wont go past the grey screen. i tried to reset the pram and that didnt help. any ideas?

 

that brought up a refresh button my hard drive and an arrow key. i chose the hard drive and advanced. now its sitting on the grey screen loading.

 

how do i delete it?

 

i dont have the disks anymore. will these work?
http://www.powerbookmedic.com/Mac-Restore-CD-with-Mac-OS-X-v105-Leopard-p-17416.html

 

i bought it used and had to borrow the leopard disk to update it. should i just find the tiger restore disk online? or is there a way i could restore it without the disk?