Problem solved. Out of idle curiosity I tried the ASUS forum, and discovered the wireless driver had been updated. I installed the new driver, which in turn installed an Intel connection utility. I ran this and was offered a mind boggling array of security details. A phone call to my ISP solved the security muddle and I am now up and running.
I do not know why the wireless stopped working, but I am now up and running. I have just noticed that the wireless LED does not seem to work. I can live with that.