Got what? The email? It goes to your Xbox account email. Maybe check the junk folder, if you have one. My email was titled "Say hello to your reward: $5 Xbox gift card"
Try logging into the bing rewards, click the little head at the top of the page, that should take you to your profile. There you can view rewards you've redeemed. Click on the card if it's there. There is an option to Resend it. Check and make absolutely sure it gets sent to the correct email.
I don't work for MS or Bing, so I can't tell you what went wrong with any certainty.