that's exactly the behavior i had the first time i encountered this problem. i spent 3 days trying every disk repair app i had. no luck. untill diskwarrior was suggested and i tried it. i figured even if it didn't work, you can never have too many repair apps. but it did and within a half hour it was back up.
another hint - don't just try and repair your non appearing disk. often the recognition problem is in the main drive and system. so try repairing it as well. you might have to run repairs on both to get it to work. i've also heard people with similar problems report results after running repairs on both 2-3 times each.
if a repair app is compatible with os x, it doesn't make a difference whether it runs from os 9 or os x. if your norton will launch from os 9, you might try it from there. at the moment techtool pro and diskwarrior are the 2 best repair apps and both only run in a boot from os 9. both have os x versions on the way. i have both and all i can say is that diskwarrior fixed this for me when no others would.
