IPod Nano 5th Generation Not detecting with iTunes

Hi,
I have an iPod Nano, 5th Generation with video and I always use MacBook to connect my iPod with iTunes. Couple of days ago, I connected my iPod with a Windows computer, to charge. After fully charged, I just disconnected my iPod from the PC and tried to listen to a song, but it freezes and I couldn't do anything.
Then I again connect it with the Windows computer and it showed in computer to format. I gave format and then tried again, but IT doesn't work. Whenever I turn it on, it just freezes and now it is also not detecting my MacBook iTunes. I'm requesting someone to help me solve my problem. I've lots of collection of audio in my iPod Nano. I want to listen to those songs. Thanks.
Masud
