Well, you could try to get them back from any backup, if Norton isn't able to retrieve them. If you forgot to make regular backups, you now know why it's important to make regular back-ups.

This is just the problem with deleting files. Their space becomes available for other files to write over. If that has happened, the data is basically lost for average purposes. If the data is real important and the cost doesn't matter to retrieve it, there are companies that specialize in data recovery. We're talking about thousands of $$$ here, unfortunately.

One other problem, of course, is when you would install another tool to recover lost files from your system. This program would probably overwrite some of the data you want to retrieve when you install it. Anyway, anything you install on your system will overwrite these lost files so the more you use your system, the more will get lost. Especially if those programs you're using are writing to (temporary) files...

Magic word here: backups! Don't leave home without them.