I have tried (present perfect) - you tried sometime in the past but when exactly is not clear or important (i.e I have tried windsurfing once before.) I had tried (past perfect) - you tried sometime within a period in the past before another event in the past (i.e I had tried fix the computer before I gave up and called a technician. I tried (past simple) - you tried in the past at a clear and certain time and the action is completed (i.e I tried that new restaurant last week, and the food was great.)