Honey, I shrunk my hard drive.

Hello folks,
I wonder if anyone can help me with a hardware problem with my WD hard drive?

I had a Windows 7 Ultimate installation on a 1 TB drive (932.5 GB formatted into 2 more or less equal partitions) and something happened when I tried to load a setup programme for my new Sennheiser headset (headsetup.exe). My Windows system suddenly crashed completely and would not reboot.

I also have a Windows 10 preview loaded on a separate drive which I boot using the BIOS Boot selector facility. Using windows explorer, I could see the files on the Win 7 drive but as I said, it just would not boot and I am assuming something happened to the MBR (just guessing). I had a backup of the drive (Macrium reflect) and restored the whole drive but it still would not boot even though reflect said that it had restored correctly.

I thought that if I wiped the existing MBR using the WD disk utilities, I could start again. That is when my troubles really started. I selected the 'quick' zero write (first and last million sectors) and ended up with a hard drive that would not initialise and showed a capacity of only 1KB.

I have downloaded several different HD utils, but none can get past that 1KB capacity. Can anybody help?