I have tried the dumpwallet "filename" option, receiving the unencrypted file,
put it into electrum and it did not show my balance.
What did you import? Note: Don't post your private keys here!put it into electrum and it did not show my balance.
Is it a private key starting with "5", "K" or "L", and 51 or 52 characters long?
Quote
When I checked the backup of the wallet.dat file, I found out that I have somehow changed it in 2017, compromising the one of 2016.
An older wallet may or may not still contain funds, it depends on what else you did after making the backup.Quote
Is there a possibility I still can access my funds or are they lost?
~
Help is much appreciated, Im still optimistic to recover the funds
How much funds are involved, if you don't mind me asking? You've been trying for a month, any computer built in the last 5 years could easilly have synced the entire blockchain by now. It shouldn't take more than a few days on "normal" hardware.~
Help is much appreciated, Im still optimistic to recover the funds