Your boot.ini file got corrupt or is pointing to the wrong physical HD. The best way to fix this is. Install NT into a new directory. Edit the boot.ini file to point the original install to the correct drive and physical HD. If you have another server that is similar scsi / ide and the same drive configuration you can use the boot.ini from that server as a model.
Reboot the server you will have two Windows NT Server selections at the boot screen I can't remember right off which is which but select one or the other if that one isn't right reboot and select the other one. When the server is back to the original installation delete the directory that you installed NT into for the recovery to free the space back up.
I've had to do this a few times if you have questions e-mail me @ timber@choice.net
Good Luck....