Help 10 points! My Windows xP Windows Font is too big how can i make it smaller?

The desktop is big , the icons are big , the bars are big the mouse is big. I tryed holding CTRL and scrolling mouse and the desktop and icons are still big. i tried everything. I think its because i uninstalled this program by accident and it restarted and it got the font big and it Says on my desktop " You may be a victim of software counterfeiting, this copy of windows did not p genuine windows validation" . How can i make it smaller like before?