If you follow the steps on this page then underneath the two security questions you will get a reset link if you do have a rescue email address on your account : http://support.apple.com/kb/HT6170
If you don't have a rescue email address (you won't be able to add one until you can answer your questions), or if you don't know what it is, then you will need to contact Support in your country to get the questions reset.
Contacting Apple about account security : http://support.apple.com/kb/HT5699
When they've been reset you can then use the steps on this page to view and/or change/add a rescue email address for potential future use : http://support.apple.com/kb/HT5620
Or, if it's available in your country, you could change to 2-step verification : http://support.apple.com/kb/HT5570