Can you see the whole address or only the first part?
If you see the whole address, copy and paste it in the blockchain.info search block. Then see if it's a active account. {Payments going out of it}
If it is a active account, you could send it a small amount of coins, just enough for you to complete the transaction. Add a message with the transaction, asking the owner of the address to contact you.
You might be lucky, and he/she see the information and they might respond positively, by sending you the coins back.
If there is no activity on the address, you are kinda stuffed, and has to write off, those coins, as a lesson learned to double check, before you send.