If you've recently changed your phone number and are having trouble with two-step verification, the most typical method of regaining access is through your backup codes or a recovery email/phone number if you've configured one. You might also need to call your service provider to activate your new SIM card.
Here is a more extensive analysis of possible solutions:
Backup Codes: If you stored backup codes during two-step setup, you can use these as an alternative to your phone for verification.
