list of "Recently Used Documents" from Start Menu Dissapeared

Hello,

When my pc is initially installed, that list is available and can be chosen
from the taskbar and start menu option but after i have installed some
software and made some changes to the "Services" in the administrative tools
from the control panel, that list from the start menu dissapears. WHY ??? I
need to get it back,what caused it and how do i make it return??

help needed.

Thanks
Robert