the blue screen problem

[mr.chanda]

Bought a Powerbook G4 from someone who had lost the disc.

upon trying to change administrator a site told me to do the following:

upon startup hold apple-s keys
enter the following:
/sbin/fsck -y
/sbin/mount -uow
rm/var/db/.applesetupdone
reboot

from then on my computer is stuck on bluescreen after trying to start up. help!