Widgets problem

Hi I have articles on my homepage right side bar which shows up ok. I went and added another article and it wont show up. I know you have to highlight the ones you want to show on the sidebar but when I go into the widgets page now it does not show up as if I have any widgets or a right sidebar so I cannot drag any widgets or highlight the article to show on the hompage right sidebar. Its been fine uptil now. Anybody have any ideas as to what has happened

Thanks