cant join one of my own worlds!

hello, so I have this world that I and my friends play a lot in. I have been using this world for about a year now. one day it stopped letting me join the said world. since I've only been able to join me every 2 weeks it lets me in once. it says "unable to connect to the world please check your internet connection and try again" so I do and nothing happens. I try everything making copies renaming it changing world settings deleting and redownloading Minecraft restarting the console. Nothing seems to work! I noticed I can only join a copy of the world if it doesn't show a screenshot of the world but the black and white screen of some Minecraft forest. please help I've looked all over the internet for something like this problem.