It's to early to tell,check your history,some body might have access to your Yobit account and withdrew your balance and beside,when you post this it's not yet 48 hours,the support usually response but they response ,some time took them 48 hours.
I am check in my history and not transaction withdrawal. I sent massage to yobit support
you have to wait several month to get any answer and i am pretty sure, they willnot solve any problem. they are always ignoring customers problems.
i advice you just forget about this worst site