The applications window of task manager shows the applications that are open, i.e. those that have an icon in the task bar (not the system tray). Processes and applications running in the background are shown in the processes tab.

So if you have just your desktop and no open apps, the applications tab will indeed be empty.

when i press clt+alt+del and the task manager shows no options like application,prosessor,preformance,networking,user button ,it just shows only only endtask,switchto and newtask button
can u help to tell what is the problem and how to solve it

Open task manager and move the mouse cursor to the blank border area near the top.  Double click the left mouse button.

Steve