Day Mode Display

the dash dimmer on the left of the steering wheel, make sure its not all the way to the top. If it isnt, move it all the way to the top then back down again. That will set your MFD to go into night mode when you turn on the lights. If you want your dash/MFD to never go into night mode when you turn on the lights, keep the wheel all the way up.
A little hard to explain, but once you play around with the dimmer wheel, you'll quickly understand.

 

Make sure that:

1) Your headlights are turned on and . . . .
2) The dimmer dial is turned down from it's maximum setting.

Then look and see if, while in this state, your "Day Mode" button has come back.

 

The dimmer wheel, on the dash to the left of the steering wheel and just above where your left knee will switch you from day and night modes if your headlights are on, BUT . . .

. . . there are actually two lighting level adjustments available via the MFD. One for "day" and one for "night."
It is possible to adjust the day lighting level darker than the night mode. Accidentally doing so can end up befuddling even long time Prius drivers. I know, I reset the display for fellow Prius drivers who had their 2004 since they bought it new. [or maybe it's that you can adjust the night mode to be as bright as day mode. I don't remember exactly, just play around with it]

When you do the adjustments via the MFD, do it twice . . . once with the headlights off, and once with the headlights on and the dimming wheel not in the full up position.

 

Thank you, it worked after 3 days of worries. I’m a newbee with 2010