You have used the Past Simple and the (incomplete!) Perfect tenses. The correct form is: 'I have / had done it'. We never use: 'I done'. I did it = Past Simple. Something completed and finished in the past. We always need some idea of time for this e.g. 'I did it yesterday.' I have done it = Present Perfect. Something completed and finished in the past, but we do not know when this happened. It could be anytime in the past up to almost the present. I had done it = Past Perfect. Something completed further back in the past BEFORE another completed past action.