broadband wireless connect problem

[denshl]

I am with BTbroadband wireless,and until recently everything worked fine but now I can only connect to the
internet via ethernet cable. My laptop uses Vista and is
fitted with a wireless on/off switch.
When I switch on from start all the indicator lights are on
including the wireless light but when I try to connect to
the internet the wireless lightgoes off and the message
"cannot find the address" appears. When I use the help
diagnostic program I am told the wireless connection is
switched off. Whatever I try I cannot switch on, Is this a
fauty switch or could it be a settings problem,and if so
can anyone help with a solution?.