Is there a way to retrieve lost Litecoin
Was your wallet not fully synced before the transaction? And still is in the same block as then?

If the answer to both of them are yes, then you may have a chance.

What you have to do is:

Verify the transaction in a Litecoin explorer

If you don't know the transaction, just input your address in the explorer and check it's balance.

If it still says you have balance, I recommend you to import your private key to some other lite client and use it however you want.

To retrieve private key from Litecoin-qt wallet, I would suggest this answer.