Question

Shall I ever
forget those happy days? (rewrite as declarative
sentence)

Answer 1

i shall never forget those happy days.

Answer 2

RULE : Transformation from Interrogative to Declarative is done by altering the meaning of the sentence.

So, we can transform the sentence as-
(1) I shall never forget those happy days.
(2) I will never forget those happy days.
(3) I shall remember those happy days.
(4) I shall remember those happy days forever.
(5) I will remember those happy days.
(6) I will remember those happy days forever.

These are the transformations you can use as your answer. Transformations (1) and (2) should be the best choice. Others are also correct.