If you have the address in your electrum wallet, you go to "Wallet" => "Private Keys" => "Export," and you will get a file with all the private keys of all your addresses. Or you can go to console and type
getprivatekeys("btcaddress")
Are you sure you send an LTC to your electrum wallet i think you will never seen any transaction if you send LTC to your electrum wallet because Electrum wallet is for bitcoin.. and i think you are using a fake electrum wallet which is it can receive LTC if ever..
Or you are talking about BTC?
There is a electrum for litcoin.