My Hp Probook doesn't display Icons even a mouse button n the desktop.

If you go to your desktop and select display, you may find that the display is set as a "double display". The right hand screen (Hp monitor) will show an empty desktop. Set it to single display.

Bad setting. If you press and hold the power button, the computer will shut off. That will keep you from having to unplug it.

You just move the icons where you want them. Maybe you are saying your can't see all your icons. if that is so, go into the display under the control panel and change your screen resolution. The higher the resolution, the smaller the icons and more will appear on the display.

http://www.retrevo.com/support/HP-6550b-Laptops-manual/id/23720dj691/t/2/
This is the users guide for your model. John

This happens when Explorer (the file manager - the program that makes all the files visible on the screen) doesn't starts at boot. Press Alt + Ctrl + Del to open Task Manager. Click File, click Run and type explorer. Click OK and the icons and the taskbar will appear. If it doesn't start or it's faulty in any way you will have to reinstall Windows.

Perhaps you mean... How to change screen resolution. Here's a quick way.
1. Minimize all applications 2. Mouse over to a part of the desktop that doesn't have any icons 3. Right click on the mouse
Depending on the version of Windows, you'll select Personalize, Display Settings, or something like that
4. Slide the resolution bar to something that you like. 5. Click Apply, OK, etc.

http://h20000.www2.hp.com/bizsupport/TechSupport/DriverDownload.jsp?prodNameId=4145436&lang=en&cc=us&taskId=135&prodTypeId=321957&prodSeriesId=4145435
select your operating system and download from below section these drivers it will start working
Driver - Keyboard, Mouse and Input Devices

is it with linux or windows?

Type search www.facebook.com to arrive at the network website. Place the mouse pointer on the list of displayed results from where right clicking the mouse button should display a list of options that allow to cut web address to be pasted on the desktop. Once the www.facebook.com has been cut from the internet should place the mouse pointer on the desktop where rightclicking again on an empty space area shouldl display the cut media. Iniiate a paste with the mouse button on the desktop space from where the new facebook icon is displayed to acessibility.

When you have your desktop up & displayed, click the right mouse button & it will bring up a menu. Hover your mouse above the "Arrange Icons By" option and it will bring up a sub menu. If the "Show Desktop Icons" option does not have a check mark to the left of it, that is your problem. If there is no check mark, navigate down to it and click on it with your left mouse button and that will make your icons display.