How can I connect my wireless-b Notebook adapter?

[Charles Keller]

I have a Wireless-B Notebook Adapter Linksys(WPC11 v.4) in my DELL -WinXP Laptop and in the "Network connection" it says:
Wireless Network Connection
Wireless-B Notebook Adapter
NOT CONNECTED, Firewalled
and I get a red cross across the icon.

I used to be able to go wireless to the internet via a router, Linksys,
Wireless-B Broadband router, Mod. BEFW11S4, and now it doesnot work anylonger.

What can I do to make it work again, e.g. how to make the connection
wireless between the Router and the adapter?

I tried to phone the support line of Linksys in India, and unfortunately
they have such a funny accent, that I can't understand what they say.
Your help would be very much appreciated.
Charles.