Reset wireless router cant secure connection!

Hello,
I have a Presario M2000 with Windows XP and hi-speed cable connection. For three years I have used Linksys WRT54G V8 wireless router with a secured connection with no problem. A relative, unable to find the Encryption Key, pressed the "Reset" button on the router. It still works fine but is now Unsecured.

I want to make it a secured connection. I have run the installation CD four times and get the message that my computer can not detect the router.

I called Linksys and was told that my service contract with them had expired (I did not know that I even had one!), and that for $39.99 they would walk me through a new installation that I could make secure.

Is there anything I can do, short of paying them $39.99, to make my wireless router internet connection secure?