I discovered something interesting, guys, look:
I did it
It's a usual sentence. We can negate "it" by:
1) I did not it
We can negate "did" by:
2) I did not do it
Also we can negate "I" by:
3) Not I did it (but he).
I know you will say: "It should be "...(but him)"" but it's a different moment.
We can make a question of the №1:
Did I do not it?
We can make a question of the №2:
Didn't I do it?
Did I not do it?
And finally we can make a question of the №3:
Did not I did it?
Because here "not I" is the whole not separatable noun. And all of it works by rules: for the question we have the auxiliary verb, then the noun, then all other things. So,this sentence will be incorrect if to think that it meant to negate the verb (The question of the №2) but if to think about it like about the negation of the noun, it's perfectly fine. Though I guess native speakers will mean it through "it":
Was it not me who did it?
What can you say about it?