Upgrade wallet balance 0

Let me explain.
I have a old ltc qt wallet that needs an upgrade (shows a message: alert key upgrade required)
So i downloaded the new version ltc core wallet of litecoin.org
when i open my wallet, fully synchronised, it shows my transaction history but no litcoins at all? balance 0
how to run using the command -rescan
changed the new one to the old one Wallet.dat
who will help 1 LTC

Hi, do you take ur Litecoin qt wallet.dat and put it to ur current Litecoin core wallet there?