We learn in Install Forum here (the #1 Win7 installation forum on the web) to be thorough enough to backtrack to steps where something might have changed, as often happens when trying multiple approaches.
Just to make sure you are running the correct command: with only problem HD plugged, boot Win7 DVD/CD press Shift F10, in Command Box type:
DISKPART
LIST DISK
SELECT DISK 0 (if it shows up)
DETAIL DISK
Report back anything listed.
If not, boot maker's Repair CD to see if it detects HD and can repair. If not it is likely dead.