Since it does not work on other PCs.
There is no need to back it up since it is just a backup and the original is still where it is.
Maybe you need to re-write your post (I goofed mine!) about this being the only and last copy.
Does the drive show in Device Manager or Disk Management?
Yes I read "manage" above but let's try to use the titles of the apps Vista came with during technical discussions.