Have a problem with my camera which has never happened to me before?

Photographers can you please help me. Please don't be rude because I asked a question about this problem earlier today and the response was rude. I have a Nikon D40x and I have noticed that the exposure button doesn't see to me working. You know like when I want to under expose pictures I use that +/- button and the dial? Well on the screen the only thing thats moving is the shutter speed and f stops. I have never had this problem before when the number beside +/- on the screen doesn't increase or decrease. I don't know if it was to do with the cold weather or the battery but its bothering me. I just have a genuine problem and really need help and don't know what to do. Pictures turning out white. I ignored it today and just used the shutter speed and f stops to take the pictures but I'm not happy with the way they turned out. A lot of them turned out very dark, so dark I couldn't even see the buildings. I'm not a 'poser' I know how to use a camera, this is the first time this has happened to me. Please please help me!

Firstly what mode are you shooting in - in manual mode (M) the EV comp button (+/-) has no effect whatsoever.

The shutter speed & f number ARE what control exposure - if they are changing then you are going to get changing exposures (again depending what mode you are in - auto modes like S and A will automatically compensate when you alter one of the parameters.

White photos indicate overexposure (ISO too high, aperture too wide, shutter speed too slow), dark photos indicate underexposure (ISO too low, aperture too small, shutter speed too fast).

IF you are still struggling, then upload an example (with intact EXIF data) to a photo-sharing site like Flickr & post a link to it here - it will be easier to see what's going wrong if we can see an example.

The nikon menu is configurable
you can LOCK things.
also depending on whether you have the turny knob set to auot/portrait/sunny/night etc
then different parts of the menu are grayed out.
you can check for yourself.

you can RESET the menu to UNDO any adjustments that have been SAVED.

really these features make the Nikon more complex than it needs to be
and this often makes people moan about this complexity.

all this adds up to needing a CHEAT sheet or at least reading one of the books
like the Digital Field Guide David Busch or Simon Stafford's Magic Lantern Guide.

pushing the AE-L(automatic exposure LOCK) will prevent changes and allow you
to take many shots whilst preventing focus and exposure changes.

There are so many variables that it would be helpful if you could say what your settings are; for example, are you using manual, shutter or aperture priority, and so on.

EV is calculated from shutter speed, aperture size, ISO and amount of available light. If the shutter speed and f/stop numbers change, EV changes too. The EV value is still out of range of that number line in the status display. You may still have to turn that wheel a lot more times for the +/- line to react. All white pictures mean they are grossly overexposed.