How do you mean here, do I just copy the wallet.dat folder into the same directory?
Where is your "old" wallet.dat?
You can either shutdown Bitcoin Core, then copy the "old" wallet.dat to the datadir shown in Bitcoin Core (Menu: Window -> Information) and replace the "new" wallet.dat. Then restart Bitcoin Core...
or
You can shutdown Bitcoin Core, then copy the "old" wallet.dat into the datadir and rename it something like "old_wallet.dat"... then restart Bitcoin Core and use the "File -> Open wallet..." menu and you should see "old_wallet.dat" shown in the menu. When you select that, you'll get a dialog pop up and it should automatically rescan the wallet for you.
As always... only work with
copies of your original wallet.dat file...