I watched a tutorial on how to make a night time scene and it worked fine but then i deleted the sky sphere and when i try to re make the same night time scene it dont work. i have all the same settings as before but instead of night time its a pinky sun set type of scene. i must be missing something. its really important that i get it night time again. any help would be very grateful. Thank you
Just add the sky sphere again and assign the directional light to it in the details panel 
sorted !! thank you so much 