No internet access

Hello,
I have an acer aspire 3680, with Vista. My wireless internet connection is through my cable company. Everytime I attempt to access the internet I get a message you are currently not connected to any networks. When I try to find a network I get the message windows cannot find any networks. When I hit the diagnose it tells me turn on wireless capability. This button does not stay on and the only was I get access is to restart the computer each time. All of this started withing the past 3 months. what is causing this and can I fix it. The cable tech told me to reset my computer to factory settings. yet when I went out of town to my family the computer picked up the network immediately each and every time.