Check that you have the latest updates installed on your computer. Your computer has to be connected to the internet to perform this.
Start by disconnecting your phone and other USB devices connected to your computer.
Switch off the phone. Connect a compatible USB cable first to the phone and then to the computer end. If the connection was successful, the phone vibrates and Zune starts.
Enter your phone's lock screen password if prompted, then you should be able to see your phone in Zune.
If your computer can detect your phone but cannot load the driver, check to see that your phone is listed under Portable devices in your computer’s Device Manager (Press the Start button, type Device Manager and press enter).