Well, you should have been doing a backup with time machine before OSX had a problem, then this all would have been avoided. But since you didn't:
Do you have an external drive as large as your internal hd? If so, plug it in, then go to utilities-> disk utility on your restore disk. Then select your internal HD from the left and then at the top select, "new image." Save this image on your external hd.
Then if the all goes well with making the image you can go ahead and do a clean install of OSX. After you complete your clean install and boot into leopard. Plug in your external hd and double click on the disk image you made. This will then mount and you can find any files that you want and manually drag them over to where they belong.