My Second Monitor is NOT working although it

Hello,

I have a Vayo with Vista on it..
I also have had a secondary Monitor working fine before the New Year ...somebody had set it up for me..
I have disconnected to take my laptop to the Party ..
When I returned today and hook up everything as before the secondary Monitor is not working..!
I have checked all the VGA connection all is fine but when I go to Settings press and check the <extend this monitor ....> I say yes, press apply and then ask me < do you want to keep the same settings I press No > OK and still I cannot see anything on the other Monitor..

What is wrong what am I doing wrong ?

Please Help !

Thank you and Happy New Year!