I don't know what to do.

I don't know what to do. (该怎么办呢?)

Don't worry, I'll help. (别担心，我来帮你。)

I'm at a loss as to what to do. (我真不知该怎么办才好。)

I'm unable to decide for myself. (我一个人决定不了。)

What shall I do? (怎么办?)

我该怎么办?

What am I supposed to do? be supposed to “计划做……”。

What am I supposed to do? (我该怎么办?)

I don't know. Just relax, I'll help you. (我也不知道。放松点儿，我会帮助你的。)

What am I going to do?

What should I do?

这下可麻烦了。

We are in trouble.

We can't finish our proposal in time. (我们不能按时完成计划了。)

We are in trouble. (这下可麻烦了。)

We're in big trouble. 进一步强调不知如何是好的心情。

那很麻烦。

It's a hassle. *hassle “麻烦的事情，苦战”。

Do you like the new computer system? (你喜欢这种新计算机系统吗?)

No, it's a hassle. (不喜欢，它很费劲。)

It's a pain in the neck.

It's a pain in the ass. 低俗的说法。

It's a lot of trouble.

这真是个难题。