It sounds as if there may be a problem with the WiFi at your house, not on the Droid.. Did you recently change any settings on the router at your house?
My brother had a similar problem with his Droid that I was able to fix. He has a D-Link gaming router, and somewhere buried in the settings of it was a check box that needed to be unchecked. Once I did that we could use our Droids on his WiFi. His laptop and Wii never had a problem connecting at all, but for some reason the Android would not connect. Do a google search for "Droid" and whatever make/model of router you are using and you will likely come up with some suggestions of things to try to get it connected.