Hard Drive Data Recovery

Hard drive data recovery?
My hard drive has stopped working, due to power failure during system restore. I have tried to access the hard drive in an enclosure from another computer. But all I get is that the drive isn’t formatted. The drive had two partitions – C and D – I know data was backed up to D but can’t access it.
Will the data be gone from D, or is there a way to get at it?
and
Do any data recovery programs actually work, will they get information back for C too?
firstly is it recognised in BIOS and the likely hood is your DATA is gone not 100% but its a good (or bad from your point of View) chance that its all gone, some DATA recovery programs work but i wouldn’t know which ones (and from now on you might want to back it up on a server from someone else (sorry)