After hearing that song, his thoughts rewound to his college days.

rewound 是动词 rewind 的过去式。rewind 由前缀 re-（表示"重新、再次"）和 wind（"缠绕、转动"）组成，字面意思是"重新缠绕/倒转"，引申为"倒回、回溯"的意思。rewound 在这里表示"思绪倒转回到过去"。