If you established a rescue email address, there will be a link on the "Passwords & Security" page of id.apple.com. Clicking the link will send the reset to your rescue email address (NOTE: This is not the same address as your Apple ID email)
If there is no link on the page, then you didn't establish a rescue email address. Contact AppleCare at 800.694.7466, and ask for account security. You will need to answer some questions to verify your identity, AND you will need access to a computer to generate a temporary support pin.