Sorry to hear that you're having issues with your controller. Could you please check the following:
Does the LED on the side of the device turn on when you plug the controller in?
What color is the Leap Motion Control Panel icon in your system tray?
What does the text say when you hover your mouse cursor over the Leap Motion Control Panel icon?
You generally do not need to re calibrate the sensors unless the software prompts you to do so.
Try swapping USB ports and cables as well to see if that helps.