With Windows XP, a new Start menu is enabled by default. Under certain conditionos, when a new Start menu is enabled, the My Computer, My Documents, and My Network Places icons disappear from the desktop. To restore them: Right-click the desktop then click Properties; Click the Desktop tab; Click Customize desktop; Click the General tab, then click the icons that you want back on the desktop; then click OK
On older systems, you could boot, go to Start -> Run -> then put a period "." in the run and run the period. That would put you back at the default screen with Icons, But I have not tried that recently.