what is the difference between how come and why??
why
"how come" is Informal: How is it that; why
"how come": for what reason
"How come" differs from "why" in that the word order of the question is the same as that of a statement. Compare:
You didn't leave. (statement)
How come you didn't leave?
Why didn't you leave?
"how come": for what reason
"How come" differs from "why" in that the word order of the question is the same as that of a statement. Compare:
You didn't leave. (statement)
How come you didn't leave?
Why didn't you leave?
"How come?" only sounds natural in certain circumstances and I don't think it is really proper English (I've been trying to think of how someone would diagram a sentence like that). "Why?" however, is simpler, better sounding and always acceptable. I would suggest using it in all cases.