lost Desktop

[jozien64]

I supervise a linux user group and we (6) all use mint 17.1.
2 users lost the Desktop icons, get a Black screen on 2 different laptops, an Acer and a Dell inspiron.
Prior to this problem, every thing was working fine.
/home/user/Desktop is still there with all the icons, how do restore the icons on the Desktop?

jozine64

[jungle_boy]

Change the wallpaper.