Did you by chance set it to Auto-Hide? Move your Mouse cursor to the bottom of the screen and see if the Taskbar appears. If it does right click it, choose Properties and under the Taskbar tab uncheck "Auto-hide the taskbar", click Apply/OK.
I have winxp home sp2 and my taskbar is not showing, so i cant use the windows start menu or quick launch, all i can seewhere it should be is black or my screen saver. Is there any softwre i can get to help me