have never been heard of since 杳无音信

“杳无音信”，汉语成语，指一点消息也没有，形容失去联系或没有方式联系。可以翻译为“there has been no news whatsoever about somebody，not heard from ... at all或have never been heard of since”等。

例句：

他走后一直杳无音信。

He's never been heard of since he left.