Once I had a drive that was completely Dead (it was old), The Drive contained so many important things i was banging my head against the wall (it had 8 months work on Programming)..About 2 days later my neighbor told me to try to plug the drive in using Linux.. I Used Live Cd Ubuntu And Managed to get every single Bit of data off the Drive, Although i did have to manually "mount" the disk, i Recovered all of my data. Although our situations are a little different You could definitely give linux a try (after all what do you have to lose)... As for what i think Norton Did is just completely screw with your partitions. Try linux (using a Live CD you dont even have to install linux, and even better its free) plug it in , at the least it should take the drive and then try to see If you can mount it to the system, If not, then i cant reccomend anything but to pay someone to help you. You could Call norton and Explain the situation (if you are very angry explaining anger always seems to work) and see if they can compensate the loss.
Finally Most external drives Using Nfts dont need to be Defragmented I have had a backup drive of mine for 3 Years now and the other day i went to see it was only 14% fragmented, as long as you don't read and write all the time to the drive it shouldnt need to be defragged.
In review Try Linux (
Download Ubuntu | Ubuntu ) it might just save you.