i spent 5 months on a minecraft world and it got deleted when I SWITCHED MY TEXTURE PACK

i lost 5 months of work because i switched my texture pack i switched to a detailed texture pack to make my world look good and see sights in it but after i logged off the next time i opened minecraft my world was gone and i was more than sad please fix it because i dont want to have to feel that again the realization that all that work just got deleted from a texture pack switch.