I guess the funds will be lost since I have created a new wallet.dat file over the old one.
So.. you want to say that you have ignored our advises to create a backup ?
Well, if you do make a backup of your wallet.dat, you can't destroy anything.
As long as you keep several backups of wallet.dat, you would be fine and you can easily switch to another backup if you mess one up.
If you have really overwritten your wallet.dat, you are out of luck. And to be honestly, it is your own fault.
You should have followed our advises to create several backups + do what we had suggested to access your coins.
I imported the Keys directly into Electrum (standard wallet--> import private keys)
If you have imported the private keys, what is the problem then?
Any coins attached to these addresses would show up in electrum (at least if you have correctly imported then; Is the first char of your addresses identical with the ones from core ?)
Mind explaining what the problem is after importing the correct private keys ? Because, for me, it seems you have managed to export/import them properly.