Is there a way, that I can know that my unconfirmed transaction return back to the sender?
The sender can try to start the wallet with -rescan option to check the blockchain for missing transactions.
If you were expecting coins, you can do the same to be sure and also check the blockexplorer for the txid.
In any case and whatever you do, make sure you have a working backup of your wallet.dat before you start!HTH
No, the problem is, the sender sent me coins and after he recover his wallet those coin goes back, so I never receive them. But he denied. I am sure this went back. So I want to know is there a way I can prove that the coin goes back to his wallet?