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I do not use online backup myself so this is not from personal experience but you should be able to see (when online) by opening Norton - select the Backup pane - select Restore Files - when the next page is displayed make sure that the online backup is the one displayed in the Restore From section, then under section 2 Files - you should have an option to Browse for Files and Folders. Does that do what you want?
Can you confirm whether you are using the online backup in Norton 360 or the Norton Online Backup program?
Once we have clarification if its Norton Online Backup or Norton 360 we can provide a definitive answer. The short one is you can take a look at what's available for restore. That will show you the content backed up successfully which in turn is what is restorable. It doesn't mean you have to start one - just review what's there.