Game not saving world progress when it hits night time

so i have a survival world that i have been working on for about 5 months, yesterday i was going exploring, and every time it goes to night time the game does not save beyond that point, everytime i load my world again it just brings me back to the place i was when it became night time i have tried sleeping and it still does not save after it hits night time, you might say the problem is in my world BUT this world has never touched a beta so it should be 100% stable, i hope you can help or at least tell me a way to fix it and if you want a link for my world just tell me thanks.