Why not lunch?
Works as well.
why not :"did you make the dinner "
Should work, added now.
'Have you fixed dinner?' should work.
The designation of meals should be: sniadanie-breakfast, drugie śniadanie-lunch, obiad-dinner, i kolacja-supper. Drugie sniadanie has not been introduced at all, and it is, after all the second meal of the day, corresponding to lunch.
Why "cook" doesn't work?
OK, why not, added.
I think that "prepare" should be acceptable as well (it is currently not).
While we can say the same by "Przygotowałeś obiad?", we do usually accept more verbs for making food. Added "prepare".
"You made lunch?" Does this work?
It wasn't accepted until now, but I just added it.
Did you lunch? is considered a wrong answer until now
That means "Did you eat lunch", not "Did you prepare lunch".
"Did you lunch?" is not correct in this case, as it means "did you eat lunch?".