Lost backup information on external drive

The live update of Norton 360 failed. I was forced to reinstall Norton 360. I create the back-ups on a local external drive. After the reinstallation all information about the back-ups were lost in Norton 360 however. 

How can I get access to my earlier back-ups on the external drive?

Thanks in advance,

Hans

I'd like an answer too, whenever I had/have to reformat my pc I find that I cannot find my backup via Norton BU or Norton Cloud, due to no link showing to said backup - even online backups are affected.
The backup is still on the external HD but are inaccessible in that format.
It did get me out of a pickle after accidentally formatting my SD card containing all my .exe program files (I backup this & another HD) all I had to do is restore it so backup is useful in some cases.

I've moved to Macrium reflect free for complete/full backup & restore, I can reinstall files/folders by opening the clone or image.