It is a little sad to hear you can not get your data out. Before thinking of any actions, can I ask a little more details on the problem
1) You were running Puppy Linux before changing the caddy for that disk?
2) "Now not being recognized by Linux" meant the same Puppy Linux you are running?
3) Have you tried to plug the drive in to a different machine?
4) What can you see when plugging the drive into the box and boot with a live CD/DVD such as Linux Mint? Can use Disks to check.