if it is encrypted you need the password that you used to encrypt it, there is no other way.
litecoin-core is very similar to bitcoin-core and they share a lot of commands. so you can search for bitcoin equivalent and apply that to litecoin core if got stuck in any steps:
in the console type:
dumpprivkey litecoinaddress
you can use the console help if necessary.
here is a helpful link:
https://bitcoin.stackexchange.com/questions/4203/how-can-i-export-the-private-key-for-an-address-from-the-satoshi-clientand when you get the private keys then you need to start a new wallet in electrum-ltc and instead of seed you paste these private keys in and make a new wallet.