Renewed thks for your kindness, especially for promptness in replying and the detailed suggestions that you send me.
Unfortunately I've had a bad experience with System Restore in the past and had to resort to a professional pc expert. I understand it is not for amateurs like me to use System Restore, so I am wary of taking the risk again.
In the case of UTUBE, i managed to retrieve the desktop icon by entering utube.com in the Google searchbox. Best regards from Joe.