How to cancel pending transaction of ethereum from exchange wallet? It is pending for around 36 hours now. There is no available tx hash.
There is no way to cancel the transaction (even if you know the tx hash)
It is most likely pending for a long time, because of the low gas price.
It might take you a few days until your transaction gets through.
If you know your transaction's gas price is under 3 it takes a long time.
For current gas prices see here: https://www.ethgasstation.info/
You can't cancel a transaction if it's broadcast into the blockchain already. But exchanges may work in mysterious ways and it might not be even broadcast (yet). Having the tx hash wouldn't help you cancel it but would make sure that it's broadcast and therefore uncancellable.
The only thing you can do is contact the exchange.