Thanks Hobo, I had already done most of the checks you suggested but had no joy. Since I share three folders I have moved them from a holding folder to my desk top in case the fact that the holding folder was not, itself, shared had, somehow, affected them.
I do have the interminable list of file suffixes but the only folder LimeWire says I am sharing is 'Shared'. I have re-booted three times after ensuring that the sharing options were correct but LimeWire still can't see my three shared folders.
Yesterday there was no problem and I am still using version 4.9.30 of LimeWire and I have changed nothing in my computer. I am totally flummoxed!