If you have a rescue email address on your account (an alternate email address is different) then you can use that to reset them : https://support.apple.com/en-gb/HT201485
If you don't have a rescue email address (you won't be able to add one until you can answer your questions) then you will have to contact Support in your country to get the questions reset.
Contacting Apple about account security : Contact Apple for help with Apple ID account security
If your country isn't on that page then try this form to contact Support : https://www.apple.com/emea/support/itunes/contact.html
When they've been reset, and if you don't already have a rescue email address, you can then add one for potential future use : Manage your Apple ID primary, rescue, alternate, and notification email addresses
Or if it's available in your country you could change to 2-step verification : Frequently asked questions about two-step verification for Apple ID