No desktop, icons, taskbar and black screen on login

Hello,
Sir,
In my TOSHIBA PC there is no desktop, taskbar, icons and black screen with cursor is seeing now. When I starts laptop I can see the welcome window and then windows media centre opens suddenly. When I close the window of Windows media centre I can only see the black screen with cursor. I tried to run "explorer.exe" and also "regedit.exe" through task manager, but I failed to run it and the Windows media centre get opened. I can use internet and some applications like Adobe reader, Word pad, Windows media player etc through task manager. My laptop is Kaspersky protected so, there is no chance for virus attack in my system. I kindly request you that please tell me a good solution for this problem. I am gladly waiting for your reply.