Formatted External USB Stick/Drive Data Recovery

My external USB stick is formatted by myself accidentally. I feel terrible now, because there are many useful and important files saved on it. I will not be happy if they are lost forever. So I want urgently to get them back now. I think I am a little crazy now. No one around me can help me recover my losses, so I hope one of you can help me retrieve what I have lost. Any help will be appreciated. Thank you any way.  –Mike from New York