4gb moserbare pendrive unable toread or write

Hello,
my 4 gb pendrive does not working from morning. nothing happens to it. but suddenly it disconnected from my machine. and after that when i connect it in usb port. it shows new hardware found but pendrive does not working. I have seen hardware devices . there it shows that it is working properly. I try it ion different usb ports.
but still it is unable to read or write. please tell me if you know any solution.