If your Coinbase account was closed without warning, it could be due to several reasons. Common causes include violations of Coinbase’s terms of service, suspicious or prohibited activity, or failure to complete identity verification. In some cases, Coinbase may close accounts due to regulatory compliance requirements. To resolve the issue, contact Coinbase support for clarification on the reason for closure. You may also want to review Coinbase’s user agreement to ensure your activity was within the guidelines.