Your information is vague and very confusing with me. Would you mind explaining how did you open an encrypted wallet if you don't have a wallet password, and how did you see the balance without unencrypt it for opening it, please.
Anyone that used Bitcoin Core can answer that; it can load and open wallets without providing the passphrase. (
Core uses the term passphrase)
But in any case, OP clearly described that somehow, the wallet.dat backup that he has isn't encrypted
And for the balance, he mentioned "
after the whole blockchain sync".
The information isn't vague at all.
I tried pywallet to dump the private keys but the none of them is the right one.
Aside from LoyceV's reply, additionally, since you were using an old non-HD wallet v0.14.2 with a keypool size of 100 (
>=v0.16.0 creates HD wallet by default, <0.15.0 has 100 keys in its keypool);
Once you've loaded it to a newer client where the gap limit is higher (
1000), it'll generate more unrelated keys that isn't derived from a seed so you wont recognize most of those aside from the old keystore.
and it probably won't work because it has been 6 years, I was told there were many electron dislocation on the nands.
You can try to recover individual keys if the whole wallet isn't recoverable.
Some encrypted private keys may have survived, I'm sure the professionals will provide you a recovered image copy of the drive where you can try various tools like
pywallet --recover.