Lost wireless network

Hello,
Last week, for no apparent reason, my wireless router stopped working. I have a newer and older model, all three different brands. I've connected them all and called the cable company to get the modem reset each as is required. I can find the network about 50% of the time once the router is connected. The 50% that I can find it, I cannot connect. I get an error message saying there is a problem with my security settings. However, I've checked the router and even unencrypted the link, still no luck. Anyone know what's going on? I can't believe all three routers are broken, but I cannot figure out why I no longer have a wireless network.

Help!
Carlos