How to restore corel draw file?

I'm new with Corel Photo Paint X3 and I must have messed some configuration because when I use the paint tool (brush) to draw a line or a pixel, it does not paint anything, I've made sure I'm using the right color, etc, etc etc. It seems to be doing something because the UNDO icon is enable but I see nothing on the screen.
I wonder if there is an option to restore the original configuration so that any misconfiguration I might have done is undone.