Did you try resetting your router?
What about updating your wifi drivers?
There is always a possibility that there someone using a device to block the wireless signals in your area...do you have cell phone service signal?
Have you tried multiple devices and double checked the wifi information is correct?
If you have multiple wifi bands with your router, have you tried each of them?
Have you tried resetting the router to factory default settings?
Have you tried a different router if possible?
Did you get any new neighbors recently, as there is a chance that other networks may be causing interference with your own.