#HD's go bad
It seems like your partition table and boot sectors are gone. The partition
table defines what type of file system is installed on a particular partition.
That's why you get FDISK telling you that's not a DOS disk. The boot sector
defines what type of hard disk you have (how many sectors per cylinder, sector
sizes, root directory size, etc.) Mirror (or image) won't do you much good by
now. It saves the state of the FAT (which I can't tell if it's bad or not).
You need to first rebuild the partition record. It has to be done by hand using
some disk editor. You will then need a new boot record. If you installed NT, it
made a copy of it for you. You should have a file in your root directory called
BOOTSECT.DOS which you would just copy to sector 0. You can use Norton stuff
for all this making sure you only copy a single sector ("from" and "to" must be
the same sector number).
If that's all that got screwed, you should be up and running. If the FAT is
also ruined, then use the FAT image to restore it. If the damage went beyond
the FAT (root directory for instance), then you will need to put the puzzle
together by hand a piece at a time.
Note that running FDISK, deleting the partitions, remaking a new DOS partition
and reformatting the disk will also fix the disk but it obviously also deletes
everything.