Unable to boot OS

On PC with win98 SE after “POST” it does not go any further, with message “insert system disk”, it hangs. When bootable disk it goes upto Pscan then hangs. Tried to reinstall, but does not find any partion, FAT missing message appears; therefore unable to see hard drive. Also unable to FDISK. Windows is there, tried to add HDD as sec/slave to read from Master from explorer but unable to see the drive. Need help to recover the hard disk.