FTB Minecraft world is not appearing to select?

I had just entered a mystcraft world i was going to go explore then my ftb crashed. When i reloaded my launcher and went into minecraft to try and get back into the world the world is gone. I looked and the name of the world still has a file in the saves file… This happened to another world before too but i gave up on it… Any help would be the greatest. Please please help me.