Shuts off and wont power back up

I haven’t had my Fuze for long and one day while walking, it just powered off. After a few days of plugging into the computer (hoping to get it to work) the Fuze powered on. It has worked for about two weeks and now it powered off again. When I plug it into my computer, it shows up as an unknown USB devise. The devise still does not power on and I cannot access it. Any Help?