Thanks for your suggestions, SmartAceWOLF and Sue T. One of the first things I did when I couldn't find my folder was to check the 'hidden files and folders' options. I only thought to do this because itunes decided to hide my music from me at one point in the past

But I didn't know to uncheck the option to 'Hide All Protected Operating System Files'. I have since done this and alas, no joy, I'm afraid.
Can you please explain what would be involved in 'asking for further assistance from a different machine'? Sorry if this is a dim question...!