How do you mean here, do I just copy the wallet.dat folder into the same directory?
Where is your "old" wallet.dat?
![Huh](https://bitcointalk.org/Smileys/default/huh.gif)
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...