There seems to have been a lot of articles about Yobit's lack of professionalism in the past days. They really don't have support and admins seem to be silent when customers need help.
You will not be able to retrieve your account. It's a exchange scam and it will soon collapse.
This is a lesson for you. Before you send your money to some exchange, learn more about it. Currently there are a lot of scam exchanges, be careful for the next time.