The first thing to do is to check that the email hasn't been caught in a spam filter somewhere. That happens a lot. Another possibility is that there was a typo in your email address, in which case you'll need to contact support at the site where you bought the game (each portal handles their own registration and support issues).

If you bought the game from LDW's site, you can email support at ldw.com or fill out their support form to get help.