The fixed expressions “if it hadn’t been for” and “had it not been for” are used to introduce a clause that expresses a condition that was not met. The modal verb that follows the expression indicates what would have happened if the condition had been met.
C2 point 91 in the category of PAST in the English Grammar Profile is defined:
fixed expressions: if it hadn’t been for / had it not been for + modal
which collocates with:
If it hadn’t been for + up to 9 spaces to the right in the COCA corpus (I changed to this corpus because iWeb and NOW corpora were not allowing or providing much information):
1 WOULD 101
I would not have been able to ever conquer my fear of public speaking,
which is where we started out,
if it hadn’t been for my fearless friend,
Dorothy Pitman Hughes, you know, for doing it together.
2 NEVER 23
3 MIGHT 18
4 PROBABLY 8
(the same search with “had it not been for” did not locate modals and the collocate frequency was much lower overall)
Up to 4 spaces to the right of “had it not been for”
From the NOW corpus:
(without the modal verb as required by point 91)
