ok, maybe if you could describe your problem a bit more i could figure out whats going on, you might want to look up on the internet some random zoom glitches, there will probably be something helpful... i'm guessing it has to do with the type of computer you have or what your settings for minecraft are, it also might depend if it's just a random glitch you're experiencing. if it's just a glitch, it will probably be temporary and it might be fixed fairly easily.