open windows do not appear in the taskbar

Hey everyone,

You know how when you open a window it also appears in the task bar so if you minimize it you can open it later? well suddenly the little toolbars no longer appear and if i want to open a minimizes window i have to use task manager. I am sure there is a simple setting i can change to fix it but i am pretty inept with computers so i dont know which one. I am using windows xp home edition.