Missing Chunks problem

I am on 1.16.0.58 beta version of MCPE which is tha latest on. When i tried to play on my survival world the world wont open and was crashing repeatedly. Then i made a copy of it and found alot of missing chunks. The world file originally was 60mb but now it says 2mb only. I dont really know if this is a bug but i really want my world back. Please fix this in the upcoming version or i wont be able to play on it with my friend. Thankyou