If you are having issues with your device, there are two things to try:
1) A Power Recycle, simply unplug and plug the device back in to see if that enables wifi connection again.
2) A Hard Reset. On the back side of the device, there is a reset button right next to the power connector, in a vent hole. Press and hold the reset button for 10 seconds until you see a new passcode and blue LED light on the display of the device. This will delete all information saved for the device. Your account information will not be removed (because it is saved in the server).