This case is solvable, and it is possible to get your funds back (if the wallet was owned by you). However, Yobit is known for selectively scamming people, and in this scenario, they are either going to ignore you or tell you that they cannot recover the funds. Although it is technically possible, consider your funds gone for good. I'm sorry for your loss. Mark my words, you won't receive any reply to your support ticket, or even if they reply, it won't be a helpful one. I've had my fair share of experiences with Yobit and my advice for you is to stay away from them forever.
A couple of days before i saw yobit's bounty campaign on this forum. It was managed by someone among their team. Even such a famous scammer exchange's campaign/bounty is been treated positively by this community. i think bitcointalk community encourages yobit to continue scamming newbies who are not known by their worst service.