How to change administrative problem

My problem started today when I tried to access task manager and it told me my administrator has disabled it! I am the only one on this computer that is networked with several others in the house. Also “run” and “shut” down have disappeared in my start menu. When I try to get them back by hitting window key and r, I get that administrative answer for it also! How to I change these setting? I can’t figure out what I did to cause this problem! Help! Help!