If Apple is trying to send a verification code to another Apple device and you don't have one, select the option that indicates you didn't get a code, then tap the option to send it to your phone number. If your phone number is no longer valid, call Apple at 1-800-MyApple. The support team is generally very helpful and will attempt to get you back into your iCloud account. It is a lengthy process, and you may have to provide proof of purchase or wait several days for a new code after your phone number is updated. Apple's activation lock is essentially an anti-theft device, so it is very difficult to bypass without proper verification.