"I do not find her."
Translation:Jeg finder hende ikke.
They both make sense but there is a slight difference in meaning. The best way of thinking about the difference is to put emphasis on the last word of the sentence. That means:
'jeg finder hende ikke' reads, to me as a native speaker, with emphasis on 'ikke'. So what you are saying is that you don't find her her as opposed to actually finding her.
'jeg finder ikke hende' reads, to me as a native speaker, with emphasis on 'hende'. So what you are saying here is that you are not finding her, but might have found someone else.