20 hours is a really long time, it should have definitely confirmed by that point, you might want to contact support. Unless you put a really low fee, then you arent going to get confirmed in a block. You might need to wait longer.
thx,i have submitted my request to the bittrex support,hope to get a reply in time.
Yup it will not take that much time to deposit your bitcoins. Before segwit2x only it will take maximum 3 to 4 hours. But now it reduced if I send my bitcoins to my bittrex wallets within 2 hours my Bitcoin will be deposited. Good and also join Bittrex slack and tell your problem they will help you to resolve your problem as soon as possible.