Translation:It did not have any effect on me.
Yok is the present.
Also compare: "I don't understand." = "Anlamadım."
See also my comment here, seems related: https://forum.duolingo.com/comment/7865162/The-presentation-is-not-over (There is no way link to the comment directly. You'll need to scroll to find it.)
Is there not also vardı for past tense? Would it be possible here? And is there yokdu (I've never seen it)?
Because "etkisi" is already carrying the required suffix i.e. "-si" Effect - etki Its effect - onun etkisi
That's how the Turkish syntax works. Dependent words are added to the left of their head words. That's why "benim üzerimde" and especially "hiçbir" can't go after "etkisi".
Thank you for this comment!
In my opinion this is a really important matter of the Turkish language.