Hi there Zeshan ali,
It would be really helpful if you can provide some more information on the issue.
You can start with something simple as just attaching the drive with a different cable to a different port. Trying the drive on another computer may be a good idea as well.
Does the HDD power up? In case it doesn't, even after trying the cable/port thing, then the HDD is most probably dead.
Is it recognized by Disk Management and how? There is a possibility that it shows over there but as being unallocated. In that case, you will need to use some partition recovery software in order to retrieve the data stored on it.
Let me know how this goes,
D_Know_WD