Hi,
Well if you mean that when you power up your computer the HDD doesn't power up (spin), one thing you can try is to gently tap the side of the HDD when pówer is on. Sometimes HDD's "dry out" if they sit too long, but don't try to open the drive, as this will pretty much render it useless. All's it takes is a small piece of dirt and it suddenly becomes a very expensive paperweight! Also don't hit the drive hard, it can cause the read arms to scratch the disks.
The above is assuming of course that the drive actually is getting power and there is nothing wrong with the motherboard (and/or IDE Controllers)
Californiakid