Unfortunately, all transactions broadcasted to the blockchain are irreversible. Once your coins are sent, it is practically impossible to recover them. However, there are some rare situations in which the transaction might fail and the money might be sent back. For example, Bitcoin addresses contain a built-in check code, so it's generally not possible to send Bitcoins to a mistyped address.
However, if the address is well-formed but no one owns it, any coin sent to that address will be lost.