I'm lost, where is the bathroom?

我迷路了，厕所在哪里？

Excuse me, where is the bathroom?

请问，厕所在哪里？

In this mall, where is the bathroom?

这个商场里厕所在哪里？

Can you tell me where is the bathroom?

你能告诉我厕所在哪里吗？

I need to go to the restroom, where is the bathroom?

我需要去洗手间，厕所在哪里？