To troubleshoot this condition boot the computer with a bootable DOS disk. After the computer has booted with the disk try to access drive C: by issuing the standard directory command
DIR C:
If the C: drive is working and you can see the directory listing then you might be able to make the drive bootable again by issuing the system command which transfers the system files from the floppy drive to the hard drive as follows:
sys a: c:
The sys file has to be on the floppy disk. If it is not then find a disk that has the file or use another computer to copy the file to the floppy disk. You can also copy the command.com file from the floppy to the hard drive by typing...
copy a:\command.com c:\command.com
...the computer will ask you to verify the operation.
Note: A drive must also have the BOOT partition activated before it can boot properly. This is done using FDISK.exe ( of course you must take precautions doing this since fdisk can make your drive useless if mis-used).
To troubleshoot problems where the hard drive hangs at boot and the computer never responds, turn off the computer and disconnect the hard drive from the ribbon cable that connects it to the motherboard. When you turn the computer back on, you should at least get an error message about the drive being bad, and perhaps go into the BIOS. Once in BIOS you can change the hard drive type to AUTO and after shutting off the computer and reconnecting the hard drive, try again to see if it now works.