Sometimes computers don't recognize what's in their USB ports for no apparent reason. Often, my computer doesn't recognize my external hard drives or thumb drives right away. Try plugging your phone into the other USB port in your computer. If it doesn't work, try restarting your computer with the phone still plugged in. If that doesn't work, plug the phone in to charge while connecting it to your computer (unless the USB cord for your phone uses the same jack as the charger.) As a last resort, bring it into the Verizon store/ call them and they should be able to help!
Check out you have insalled the Pc-suite software and usb drivers on your pc. because without both the softwares you can't get access on your pc.
Looks like you aren't the only one with this issue ... there are some helpful ideas you can try here: