Does it spin up when you start your computer?
(Either touch it, or put your ear to it to find out)...
If it does, what happens when you enter windows?
(I know you said it didn't find it, but try one more time)
If it is littered with bad sectors, use a zip-lock bag and follow SNGX1275's instructions above... (I'd say around 30 min. in the freezer should be about right...)
NOTE: Don't use chckdisk or scndisk to scan for bad sectors after you've had the drive in the freezer! You'll have a very short time that the drive works before it'll be totally dead!
If it doesn't spin up:
Have you swapped this drive much in and out of the system? If so, try applying some pressure (not much!) to the powerconnector, and move it around a bit to see if it'll start then (You'll have to do this with your 'puter on!)
If it starts, hold the powerconnector in that position, boot into windows and see if you can't copy all the info you need...
NOTE: If you get lot's of bad sectors, do the freezer... But you'll have less time at your disposal, so make sure you can find the "sweetspot" for the powerconnector!
If it has none bad sectors (you don't have a problem copying data), contact the hdd manufacturer and get a new controller card... That should add a couple of years to that hdd's life...