My MP4 player hanged

Hi,

My uncle bought me a MP4 player from China. It has amv player(for video) and wma file support for audio. I have seen the sample files come along with it. When i try to transfer one amv file it shows connection error and disconnected. From that time i was unable to get into it. It always shows proccessing symbol and nothing else. How can i bring it back to normal position. Please help me