Let\'s define term incorrect address. Incorrect address is the address that you type in accidentally or with the purpose, it is not important if someone is using that address or not. Addresses could be valid or invalid. If you are lucky and you accidentally send your asset to some invalid address, some part of the network so called nodes or miners won\'t let you to proceed with the transaction or simpler your transaction will not be verified and this transaction will be rejected and refunded to you.
When sending some cryptocurrencies to someone, the best advice is to double check the address, because there are some cryptocurrencies which may not have safety checks so you can lose your refund. Another scenario different from the above mentioned is when you sent your Bitcoins or any other cryptocurrency to incorrect but valid address. In this way, your asset is gone forever. Cryptocurrencies protocols are irreversible and transaction can\'t be cancelled.
The better scenario is when you accidentally send your coins to some address and you know who it is, you can ask them to give your money back. This scenario could happen when you send Bitcoins to someone with who you were recently trading.
It is also happening that people are accidentally sending coins to their previous addresses. You don\'t have to worry if something like this happen to you, if you know the private key of your previous address, addresses can be used multiple times.
As you can see, there are some scenarios when your cryptocurrencies could be returned to you, but there are also scenarios when you lose your cryptocurrencies, so the best advice is to bee extra careful and focus when you are sending your digital currencies to someone.