Blockchain and Cryptocurrencies are still in their early stages of development. You have to be very careful when dealing in the cryptocurrency space, as all transactions are non-reversable. If you send coins to the wrong address, they are essentially, lost forever.
Always back up your wallets
Always make sure to double check addresses that you receive and send transactions to and from.
If you lose your wallet, the only way to recover your funds is to have already backed up your private keys / seed words.
DISCLAIMER: We are not financial advisers, and this is not financial advice! Cryptocurrency is highly volatile and you could lose your money if you are not careful.