Dell Inspiron not detecting wireless networks

 I am having problems with my laptop with windows vista, can someone please help me out?  A couple days ago I had comcast install high speed internet with my modem and router, and my computer detected the network (along with other networks) and connected just fine.  The next day I accidently left my computer unplugged and the battery ran out. Since then the computer will not detect any wireless networks.  If I physically plug it in with ethernet it works fine, and I have other devices that connect to my wireless network.  I have tried disabling and enabling the wireless adapter under networks and sharing, but this did not work.  I have also tried to download the wireless driver again, but I'm not sure if I am doing it right (do I need to delete the previous driver? and how?).  I have also tried reseting the modem, router, and computer.  Any ideas? Please help.