the reason for this issue is most probably because Yobit doesn't have that particular coin to pay you with. their wallets are empty. you either have to wait until they fill the wallet, go to their cold storage, or cancel your withdrawal and give back the money to your account balance.
there is sadly nothing else you can do.
After Yobit.NET's support ticket is issued, how long will it be reply?
Can anyone tell me?
it depends on your issue. i think different people handle different kinds of issue and also based on the issue it may take longer than usual.
for your problem which is withdrawal related, it will take a long time. a week is in the ballpark.
in the chat you will see the Moderator with a green username which will make it stand out. but i doubt they can help you with this kind of issue though. but it is worth the try.