Have a bug where I cannot create a new world or open older worlds

I've had a bug after a couple years of MCPE...I don't know where it started or how. But I have been unable to create new worlds. Every time I click Create New...It loads, but then it stops and says "New World Can't Be Opened". And the older worlds I made I can't even open... it says, "Couldn't open World"... This also affected my world when I bought the mash up pack with the winter world. I couldn't create the winter world Map since I couldn't even create a new world. I can't even start add-ons or resource packs. I've had this bug for several major updates. Can someone help? Please fix this soon. Yes, I know there are similar bugs but in this one, my game doesn't freeze, it just never opens. I am getting agitated now.