IBM thinkpad centrino (everything is running but my screen is gone?)

I don’t understand it starts up right, I can hear it running, everything is working but my screen is completely black once the windows xp loads up. I don’t know if one of my settings has gone mad or what. But is it possible to adjust display settings to fix this or perhaps restore the system from DOS mode, or rebooting? please if your not busy or can help I would be so grateful