More details would be helpful to diagnose. Are we talking about icons or the entire shortcuts? Are we talking about the System, Personal or All Programs area? Post a screenshot if youre not sure...
Click on the Start button, the Start Menu opens, right-click on the Start Menu -> Properties -> Store and dislay recently opened programs in the Start Menu. With the other option you can use the Recent Items + jump lists in the Taskbar. If you want to manually add & pin Icons, go to All Programs, right-click on a Program shortcut -> Pin to Start Menu
If you click Properties -> Customize: you can edit your Start Menu + select how many programs you want to display in the Start Menu, or how many items you want to show in the jump lists.