Hi,
First, backup the hdd.
You should not attempt to install anything on the hdd this may/will destroy areas of the hdd that you want to recover.
You should use a LiveCD to boot the system. I suggest that you look at '
UBCD' or '
SystemRescueCD' and use '
Test-Disk'.
These links and others can be found at '
Slackware-Links'. More than just SlackwareŽ links!