Can't log into game and stuff keeps despawning

When logging in to Minecraft pocket edition, after a screen comes up saying 'Building Terrain', another screen comes up saying loading resources. I've been waiting 5 minutes and the game still won't load. Sometimes when I first load the game, before I pick my world, the game won't load. And finally one of my previous world's I logged into, all my animals had despawned including my horse with diamond armour.