“no wireless networks were found in range”

even though my home wireless network works fine, my Sony Vaio does not detect the network. It used to work fine, but I just came back from a trip where I connected on another wireless network. Every now and then I see the message “wireless network detected, click here..” in the bottom right corner of the screen, but when I click on that or on “view available connections” I get the message “no wireless connections were found in range’. I tried hardwire connection and that doesn’t work either.