Achievements and Mobs

All of my worlds have set to creative eventhough no one has touched the console (xbox) and now I don't have the ability to gain achievements on my previously survival worlds. And all the mobs on the worlds keep freezing completely, I went mining once and there was a creeper frozen and when I shot at it using a bow it didn't hit it and when I used my sword with fire aspect it only lit up with flames for a brief moment.