"What should I do?"
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？
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.