It could be that you have the slider to the far right of the colour picker (the 'Luminance' slider) set right at the top of its range. It's easy to miss as the slider isn't very big.
If yoru colour-picker doesn't look like the one in the attached picture, open the menu on the colour picker using the small upward-pointing arrow, and choose the HS/L picker.
Now check your luminance slider is somewhere near the middle, and your current colour is something other than white or black.
Paint a bit and see if you have colour back.
If not, there might be a problem with the ArtRage preferences file. Quit ArtRage, and seach your computer for the file called ArtRage.prs
Delete that file and restart ArtRage. You should now have all the defaults back again.
AndyRage's mantra for graphics engine code:
"Sure - how hard can it be?"