Icons On Desktop Missing Default Icons

Your icon cashe has been damaged by something you downloaded then ran.
Hold down Ctrl and Shift then press Esc, this will bring up task manager
Click on the processes Tab then search for explore.exe NOT iexplorer right click on it then then choose end process
All your icons on your desktop will disappear
From Windows Task Manager click on file then click on new task (run)
type this %USERPROFILE%\aPPdATA\lOCAL (or copy and paste it from here)
hit OK
A folder will open;  on the top right in the search type IconCashe.db
this will only work if you have hidden files and folders checked in folder options.
If you are unsure go to tools then folder options from the folder that just opened, click on view then make sure that Show hidden files , folders and drives is ticked.
Once you have found IconCashe.db right click and delete it
Go back to Task Manager, click on file then New Task (Run) and type explorer.exe
All your icons will reappear with the default icon.
There is meant to be a program called IconCache Rebuilder but I have never tried it.

This worked for me.