By using single user mode I typed "/sbin/mount -uw /"&"passwd root"
&"touch /var/db/.AppleSetupDONE"&"reboot" and then
I used "cpus=1 -f -x" (safemode) it worked and I could make my account & passwd.
But I was able to make Leo boot by no option........
It show "Darwin Kernel Version 9.1.0: Fri Nov 16 14:50:43; made by ToH:xnu-1228.0.2~1/Build/obj/RELEASE_I386"
Anyone tell me the solution of boot issue.plz ;P