Excuse me. My kid is missing on the crowded street. Can you tell me what I should do? 打扰了，我的孩子在拥挤的人群中不见了，您能告诉我该怎么做吗？

Then I'm afraid you have to broadcast it. 那么恐怕你必须得去广播一下了。

What can I do? 我该怎么办呢：

Excuse me, my passport is missing. What can I do? 打扰一下，我的护理不见了，我该怎么办呢？

Please calm down. And where did you lose it?  冷静，你在哪儿丢的？ 

Sorry, lave no idea. 抱歉，我不太清楚。

Well, this makes the thing tough. 恩，这有点儿难办了。