It might sound as a dumn question, but can somebody with knowledge please help me?
A friend of mine discovered an old darkcoin backup folder (appdata directory). He says that maybe there might be something left there (maybe a bit, but still). Is there a way I restore this wallet? Please provide clear instructions if it's possible.
Most important thing to do first.
Copy the wallet.dat file from that folder to at least 3 usb sticks and put them away.
And then take one more stick and copy it to that one too
Then, download the new core software, install it and start it. it will ask you if you want to create a new wallet.
At this point, you can just exit the software, cancel. (I am a unix guy myself, so adapt this to windows).
By now, you should see a folder called dashcore, or Dashcore or something similar, with a wallet.dat file inside (maybe).
now, copy the walled.dat file from your old installation - the one you have backup of on those usb sticks - to the dashcore folder.
If you start the Dashcore software now, it should pick up the 'old' wallet.dat and start straight away.
Wait till it downloads the blockchain, and enjoy your Dash.
as usual, don't take any responsibility or liability. Your Mileage May Vary.