If it is not a problem with brain chemistry (you might want to check it at doctor), the rhythm may turn back when you force yourself to stay awake during the day. Not even short naps. Eventually your body will give up and fall asleep at evening.
Another thing you can think of is light. Are you brighter in the dark or in the light? You can always change lighting inside a house. What about sounds? Is it too quiet to sleep at night?

Don't know if this helped, sending hugs.