Lost.Achievement cancellation

So I had exit off my Minecraft world late last night then when I locked back on for some reason I am no longer able to get achievements.this is really upsetting because I've pored over 250 hours into this world and to have all of my energy shot down by the fact that apparently I cheatedI have never ever had cheats on cheats are not active and I have not gone into multiplayer yet so for me to no longer be able to get achievements is outlandish