Renewed thanks for elaborating on your first reply.
I have tried the second method you suggest, but my problem is not solved: the desktop remains blank.
I went to my external Hard Drive and tried to shift the icons from there to the desktop, but every icon stood on the desktop for barely two seconds before it vanished again..
Could the solution, perhaps, be a reduction of the resolution? But how to do it?
Grateful for your patience.

Joe Busuttil ( 86-yr-old civil service pensioner, often perplexed by computer navigation...)