If you have a full backup of your WD install from the failed drive then using the Move WD to a new computer FAQ should help.
http://discourse.weather-watch.com/t/10888
If not then you will need to send Brian an email asking for a new registration number, you would have to generate the code first from your new WD install and send it and proof of purchase to his email address, he is the user ‘windy’
-Bob