Will not change gear and feels very loose

So basically, I was just driving around town and suddenly at one point, I was about to change gear and gearbox feels like it popped out. I could not change gear and the gearbox felt very loose, like I could just move it by one finger. However, I still could drive home somehow, I did not need to change gear or anything but I still could reach forty mph. As soon as I got home, the car could not move. Every time I started the engine, it just bounced forward and it could not start the engine? Any ideas why this happened?