After using orbit camera I would like go back to the starting point position for all objects.
Reset transform and position of the Null object has no effect after using the orbit camera.
If I use transform reset directly on the camera all objects move outside the working area.
My question is simply how to re-positioning everything to the point before the use of orbit camera.
Parenting the camera to the Null is a good practise. But once u parent it, just use the null to move the camera. If u want to orbit, I normally just rotate the Null, then set the keyframe. Do not orbit the camera itself.
To go back to your ori position, set the keyframe for position and rotation on 1st frame. So just copy this keyframe anywhere u want it to be.
Split your view to two window, which one of it try to view from top angle.
Then u have more understanding of how the camera react.