I recently finished my build and my wifi was working great and all was good. Today I got home from work and my computer had been on while I was away. Well long story, short....I couldn't connect via wifi. Infact windows isnt even recognizing my intergrated wifi card on my z77 Mpower mainboard... Under devices it recognizes I have an Unknown Device.... I deleted the drivers and tried reinstalling them... but when I did windows informed me that I could not download drivers because the device was not connected.... I'm out of ideas..
Well, have you tried opening up the computer and checking the connection?
Also, in my experience, especially with my external hard drive, Windows is a bit spazzy and requires a reboot to properly work. I usually get an error about "This device can not start" when the hard drive doesn't want to work. I only have this issue on Windows.