Is this a SATA Drive or IDE? What do you have those settings per that info set to in the BIOS?
If it is an IDE Drive be sure you have the jumper in the correct place, and the drive in the proper place on the cable. Master is the end of the IDE Cable, slave is the middle.
Can you test this drive in another PC to be sure it is OK? Is this a New Drive? If it is brand new, you may just need to set it up with the Manufacturer tools. Download them here, diagnostics and the tool to setup the drive for first use.
WD Support > Downloads > SATA Hard Drives > WD Caviar Blue / SE / SE16 (SATA II)
That is a general link, pay no attention to the drive listed the software is the same for all drives. You want the Lifeguard tools to setup the disk for first use, some disks require this before you can use them as it sets the disk active and formats it.