Then you should set sky gfx to Caelum, ingame on your top menu bar > settings theres a slider wich can be drag by your mouse cursor, like that it must change the time
but as far as i can remember a numpad is no needed since you have Plus & Minus in your keyboard so you could try, cant remember right now if it works, has been a while since i stopped to use my laptop keyboard and cant confirm it because its broken.