Sorry, its version 11.8 which I upgraded to the latest now.
The easiest probably would be if you move your wallet.dat to another computer with core installed (into the data directory, usually located in
C:\Users\USER\Appdata\Roaming\Bitcoin).
Then you will be able to dump the private keys using these commands:
walletpassphrase "YOUR_PASSWORD" 600
(to unlock your wallet for 600 seconds)
dumpprivkey "YOUR_ADDRESS"
(to dump the private key)
Note: Do not delete ANY wallet.dat files. Only rename them. This way you can't mess up and accidentally delete the wrong file.
Hello,
sorry I have not replied earlier.
I had to find a nice Computer to dump the key into.
Now I am able to use one, Im good to go

Since my knowledge is very much limited to the basics, I would like to ask for some more help.
I have a question regarding the second command.
The:
dumpprivkey "YOU_ADDRESS"
where can I find the address I put there? Is it the public address of my wallet?
I do not own the public address anymore, I just have the wallet.dat + passphrase. Will it be enough to enter the "new" pub key to the dumpkey command?
thanks in advance
Jimbo