Use the official password reset flow on Coinbase's website/app. Check your email for the reset link. If you don't receive email, check spam and email filtering rules.
Common reasons: phone clock out-of-sync, using an old backup code, or the wrong account set in your authenticator app. Try resyncing or use backup codes. If you still can't, contact official support.
Check sender domain carefully, avoid clicking links in suspicious emails, and prefer visiting Coinbase directly by typing the known URL. Never divulge your password or recovery phrase in response to email.
Log in from a recognized device, then update your security settings in account settings. If you cannot access your account, follow account recovery procedures described by official support.