The fail of hard disk
When the Spindle Motor does not activate.
When the Partition Table has been deleted.
Missing Operation System
Invalid Media Type
Deleted Data
Formatted
Overwriting
Low-Level Format
  Missing Operation System
 
1.

This is a problem of not booting. The safest way to recover your data is to boot through the a:(FDD).

Yocan also copy the Command.Com file.
   
2.

It can also fix it by Norton Disk Doctor. .