“我真的不知道”用英语怎么说？

I really don't know./I don't konw really./I really have no idea (at all).
我真的不知道。

I really don't know!

I don't know at all.

I real don't now

I really don't konw.

参考:
I really don't know it.

I know nothing about it.

I don't know it at all.

I don't know what happens indeed.

It's indeed,that I know nothing about it.