On power up, drive clicks several times at 1 1/2 second interval then stops trying to start up.
When I came in this morning it was quietly ticking away. Task manager showed a process with 48 GB disk read bytes probably from defrag software I run. This was over a five hour span.
This drive holds my full system (mutiple drives) backups.
My system was in the process of recovery from a corrupted ID. Microsoft said the corruption occurred because IE7 had too many tool bars.
What can I do to reactivate this drive?
You can try turning the power on/off a few more times, just in case you get lucky.
Also, if possible, remove the drive from the enclosure, attach to your PC directly via an IDE connector, turon on the power and see if you can feel the drive spinning at all.
As this is your backup drive, perhaps you have that data elsewhere, and replacing the drive with a new one may be easiest. Next time I recommend a Seagate drive rather than WD.
If file recovery is important enough, contact Gillware (http://www.gillware.com/). They have a $400 special price and you don't pay if they don't recover.
Good luck.