China's MP4 that can't be used anymore due to the format process.?

Yes, finally, you guys are my only hope. This story is not 100% real but duhhh, just stick to it. I just bought a mp4 from china. One day, my heart suddenly feels like I want to format the mp4 to put new songs. Then i made it. Err, so, after the format process, it seems that i can't open my mp4. I DONT KNOW WHY. HELP ME PLEASE PLEASE PLEASE PLEASE. I STILL WANT TO USE IT!