Thanks Narada,
Regret that I have done all that. Fact is that C is now OK and the puter recognises D in all areas, BIOS, FDISK, WINDOWS. I even know that my data on it is there, I have seen it scrolling by at a fair rate of knots with a recovery disk that stopped suddenly due to an error. Just enough to make out the files I want!
Problem is I can't access the drive.