How to put the icons on the desktop

I have acer laptop I do not know which button I pressed the wallpaper is white and I have no icon on the desktop and the taskbar is no longer visible
someone could give me the handling to be done?

By pressing the symbol windows keyboard (bottom left, between Ctrl and Alt), the taskbar should reappear. Right click on it, properties, then select "lock the taskbar" and Deselect "automatically hide the taskbar"

Thanks for information

But still my wallpaper is blank

Right click then click on properties -> Desktop then select wallpaper which you want.