World Disappeared/Vanished

I was going to play on my favorite world that I’ve been playing for months. As usual, I logged on and clicked play and all of a sudden my world wasn’t there anymore. I am 100% sure that I didn’t delete it. I could even play it last night. But this morning it was gone!! All of the progress I did with my sister was gone. I had super big projects and all of it was gone. Please help me get back my world.