你怎么了?
What's the matter? *用于对方身体不舒服或对方有什么异常时。
What's the matter? You look sad. (你怎么了?显得这么伤心。)
Nothing. I'm just tired. (没什么。我只是累了。)
What's wrong?
Is anything wrong?
What's the problem?
Is something bothering you? *bother “使……烦心”、“折磨”。
你没事吧?
Are you okay? *用于对方发生什么不好的事情时。
Are you all right?
到底怎么回事?
What's going on?
We were just talking. (我们只是说说。)
What happened?
What's happening?
你有什么心事吗?
Is something on your mind? *be on a person's mind “有什么挂心的事”。
Do you have something on your mind?
What are you worried about? (你担心什么?)
What's on your mind? (你担心什么呢?)
Is anything bothering you?
我担心你。
I was worried about you.
I was concerned about you.
by the way"What is the matter" it seem not good.I think,"What is up?" or " how about you?" "Are you OK?" will be better.
For my feeling , we can express what we said, but if they hearing is feeling good? May be can say"take care!"