My Minecraft World Won't Load?

I had recently downloaded Minecraft 1.9 off of the official website. I loaded it and it worked fine, and I put a lot of hours into a survival world. Just tonight, I opened the launcher to make a new world. I created it, and it loaded up. However, once it had put me into my game (that short time period where the world is blue and you fall into the void), it suddenly crashed. It does this every time I try to make a world, or load into my already present world. How do I fix this?