_I remember that one time I was wandering in a mine and when I got out I was scared MB) because I thought that I will end up getting killed by mobs, but I got home safely and On my way there I realized that all mobs disappeared. I thought that it was some sort of random, rare event, in witch mobs don't spawn. "Ok...I am happy that I got home safely".
_
A few in game days later I realized that the world was broken! I tried screaming in the middle of the desert for mobs but none came to bite me.

*The funny thing is that mobs that previously spawned remained in the world for example I found a few creapers close by my house (200-300 block away or so, but surely they were in another chunk).
*
Anyway I would atach the map but the file size is over the permitted 10MB