Don't worry. its not the first time yobit gets a DDoS and it wont be the last. It will be over soon I'm sure and trading will start again.
I know its frustrating and I'm frustrated too but there is nothing we can do but just wait for now.
Seem like the admin didn't give any updates regarding it so they resort to send DDOS.
Maybe they finally decide to add the coins users have been requesting to add. now, they were updating and under maintenance for it.