For everyone who needs a "guide" to import private key

As said before, send your LTC funds to a new address.

Retrieve the private key for your old address(es) from your litecoin wallet menu: help-debug-console type: dumpprivkey and your wallet address to retrieve your private key.

insert your private key in your LCC wallet, don't rescan untill you imported all you private keys.

I hope this helps, if not may'be you gotta stop with crypto and search for another hobby