After his disappearance, lots of people were looking for him and in the end they tracked him down!

disappearance 是由动词 disappear（消失）加上名词后缀 -ance 构成的名词形式。dis- 是表示"否定、相反"的前缀，appear 意思是"出现"，所以 disappear 字面意思是"不出现"，即"消失"。disappearance 指"消失的状态或事实"，即"失踪"。