They will try to find your registration code and e-mail it back to you, so make sure it hasn't gone into a junk/spam mail folder.
If they haven't responded yet, please provide us an idea regarding the amount of time since you initially requested.
Also, please make aure that you submitted your request properly using the information in Lost Registration

Yes, I know you didn't really lose your registration, but the fact is, you can't find your registration code, so it might as well be lost.

Worst case scenario, and I think you should wait a few days (maybe a week) before using this option, is to e-mail Khaled directly.