What i know will work:
@Active Partition Recovery bootable ISO burned to disk (partition-recovery.com for the download and instructions)
Boot the CD created with @Activate and run the partition recovery saving files to the new drive.
Other than bootable recovery software your only other option is to remove the drive from the enclosure and put the disk into the tower and see if explorer sees it now.
I run into this problem ocassionally when using drive enclosures.
also a tip. if you have trouble with drive enclosures (typically the 1 USB cable style) You want to enable disk caching when writing data to the drive, and disable it when pulling data from the drive.
Sometimes all I need to do is run a linux live disk to recover the data, then you can have windows format the drive.