怎么办 alone means "What should I do". No additional words are necessary.
Came here to say the same thing.
If you wanted to ask exactly "What should I do?" then the Chinese would be 我应该做什么？
Isn't this "How should I?". Where is "do" in the Chinese text?
办 means "to do, to handle, to manage". So literally the sentence means "How should we handle [it]." But 怎么办 is also a set phrase meaning "what to do? what should I/you/we... do?" So you could also just say 怎么办 without 我应该 to express the same thing.
Ban means 'do'.
应该 - should
怎么 - how
办 - do; manage
我应该怎么办- How should I do this
2020/02/17 I wrote 怎么办？ and got marked wrong.
Is it wrong to say, "Wo zenme ban?"
In fact, when a Chinese is asking what to do, they typically simply say 怎么办 (or 我怎么办)? The reason 应该 is required in this case is the prompt is asking What should I do.
I totally wrote this too. I (and Chinese people I knew) would say this all the time.