unfortunately second hand/used games cannot be reregistered nor transferred to another account the code is tied to the original owners account
on the other hand since you had an account and cannot remember the account details for lost/forgotten/merge accounts contact CS they may be able to assist with finding that account and perhaps help with your original game if it was ever registered
if in the event you need to contact CS
1.https://help.ea.com/en/contact-us/
2.Click on the orange NEXT button
3.Select a platform
4.Click on the orange NEXT button
5.Select a topic and describe your problem in a few words
6.Click on the orange NEXT button
7.Click Chat Now to chat with a Game Advisor
guide on how to contact CS
http://answers.ea.com/t5/Beta-Archive/How-to-contact-a-Game-Advisor-using-the-new-EA-Help-page/td-p/2161281
