The official pywallet thread is here:
https://bitcointalk.org/index.php?topic=34028.0There is a link to recover wallets in the OP that leads here:
https://bitcointalk.org/index.php?topic=38004.0However, if a simple "dumpwallet" is not working on your wallet.dat file, you'll likely need to put the wallet.dat onto a (small) USB thumbdrive and use recover from there. "Recover" cannot be run on a file, it needs to be run on a device!
Also, if your wallet.dat was created with newer versions of Bitcoin Core (ie. v0.13+), chances are pywallet will output a lot of errors about unrecognised data.
Basic "dumpwallet" goes something like:
C:\Python27\python pywallet.py --dumpwallet --datadir=D:\directory\with\wallet.dat
So... if you have your files in D:\wallet_recovery your command would be:
C:\Python27\python pywallet.py --dumpwallet --datadir=D:\wallet_recovery
As mentioned, recovery needs to scan a device... so I recommend a smallish USB drive to save time. The smaller the better.
Assuming you have 1GB thumb drive, mounted as X: and you want the recovered wallet to be put in "D:\recovered_wallet", then your "recover" command would be something like:
C:\Python27\python pywallet.py --recover --recov_size=1Gio --recov_device=X: --recov_outputdir=D:\recovered_wallet
Change X:, the recov_size, and recov_outputdir as appropriate. "recov_size" should be set to the size of the USB device 1GB = 1Gio, 8GB = 8Gio etc...