when disconnected and all items from the Help section of the User manual don't work, it's time to bring it back to the shop to have it repaired. You might still have warranty on it.
Are you sure your USB-port is correctly functioning?
I have a Creative Zen Vision: M 30GB mp3 player. I tried connecting it to my computer using the USB port. When I did this the player turned off and wouldn't turn back on. I tried hitting the reset button but it still won't work. Thanks for your help.