Try booting up from your original or snow leopard DVD by inserting the disk, hold down the the C keys while booting. Run Disk Utilities. Or you can use another type of external USB source.
Pre-Installed MacOS:X 10.5.7 (9J3050)Maximum MacOS:X 10.11.x*
You can also hook it up to another Mac and boot into Target mode using a firewire cable and see if the internal drive mounts on the other Macs desktop and repair it that way.