By default when sampling colors in Photoshop with the eyedropper the color selected shows up as the foreground color, currently when i try sampling a color it sets it as the background color -how can i fix this error? (any clues how this change occurred?)
You need to left-click on Foreground colour swatch in your Color panel. The tricky part is to determine if Foreground or Background colour swatch is selected.
This is probably what you have now:
And this is how it should look like: