I think you will need to fdisk and partition the disk again before trying to install the O/S. This of course will lose everything on the disk, but if it won't boot now then you are not losing anything. Go to click here and download a bootdisk for whatever O/S you plan on installing. Then start your computer with the bootdisk in (make sure the BIOS starts from floppy first). and then fdisk and set the partition. When that has been done reboot with the floppy disk and format the hard drive. Now install the operating system.