I do not know what to do.
我不知该怎么办。
A: You look so upset. What's wrong?
甲:你看上去很沮丧。怎么了?
B: I don't know. I do not know what to do.
乙:不知道。我不知该怎么办。
He was at a loss to know what to do.
他不知道该怎么办。
I've no idea which way to turn.
我不知道该干什么好。
I really have no idea what to do.
我真不知道该做什么.
I am at my wit's end.
我不知所措了。
I give up.
我放弃了。
A: I give up.
甲:我放弃了。
B: Why? There are still hopes.
乙:为什么?还有希望的。
I drop.
I quit.
I surrender.