Salvaged possible wallet from corrupt HDD ... now what? In short, 


I bought a few BTC years ago when they were very cheap.
I reformatted my HDD and reinstalled the OS.
I have used PhotoRec and
http://www.cyplo.net/2012/04/01/bitcoin-wallet-recovery-photorec/ to
recover 3 .dat files. Searching only for the ''detection signature''
of a Bitcoin wallet.dat


And the confusing part (if reformatting a hard drive containing bitcoins was not confusing enough!) is that the recovered .dat files are 7GB , 13GB and 8 kb.

Obviously, trying to use the recovered wallet.dat with Bitcoin-qt failed. 

Chances are that these .dat are not wallets but I though this would be worth a shot considering how massively more valuable BTC are compared to 3 years ago. 

Anything I can do with these recovered files?

Thank you!
Install Python 2.7 and download pywallet to your c:\ drive. 
Copy your corrupt wallet.dat file to c:\ 
Open a Command Prompt and type:

C:\&gt;pywallet.py --dumpwallet --datadir c:\  --wallet=wallet.dat --recover --recov_device=c:\wallet.dat --recov_size=416Gio --recov_outputdir=c:\


It should extract all the keys to a new wallet on c:\ 
Copy the new wallet.dat to the c:\users\USERNAME\Appdata\Roaming\Bitcoin folder 
rename it wallet.dat. 
Start up Bitcoin-QT with the --rescan switch. 
It should take a while, but eventually it will start up and your coins are back.