Hi, my Hitachi HD can not be identifed by BIOS,with 'clicking'
data in it is very important for me, Help me!

my god, there are so many reasons which cuasued this states.

i suggest you send your HDD to a pro.

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I just love the world.

Almost certainly heads.

But could also be PCB or f/w problems.

Have seen clicking Hitachi drives with all these causes.

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Thanks for all your kind ideas, but I could not send it to a pro.
all the data is my several year's efforts.
it is not possible for me to let it open to the public
so I am seeking any software can solve my problem
is there any good suggestions
if it's FW problem, will it be fixed only by software
I have got that software can only recover files that are
deleted, fomated and lost due to virus.

I sympathize, but I'm afraid sometimes we can't change reality just because we want it badly enough. There is likely no software that can fix this drive. Heads have to be replaced, by very skilled hands. You could try, but you will more than likely ruin anyone's chances of recovery. A PCB is something you might try yourself, but the odds of success are small. Firmware repair requires expensive tools, and the proper knowledge.

If the data is very important, you should consider sending it to someone. Any self-help remedy decreases your chances of seeing your data again. Most DR companies don't have the time to look though your data, and only look enough to make sure it's intact. Most don't keep your data very long either... Storage space is expensive, and always needed for other customers. Also, some may be willing to offer a non-disclosure agreement.