I'm a newbie and was wondering what to do when there is an unconfirmed transaction on Blockchain.info. Can I reverse the transaction? Will my BTC reach the other side? Or are they lost?
If your transaction doesn't confirm, and the sender (blockchain.info/wallet, in this instance) doesn't re-broadcast the transaction then the transaction should disappear from your wallet, as if it had never been made.
This may take a day or so.
If the transaction is being re-broadcast by the sender then it can stay there as long as the re-broadcasts are occurring.