(could not get pywallet to work for me)
Have you read
[GUIDE] Recover your deleted keys? It's in my bookmarks with the name "use pywallet to search entire partition". This should get you started.
I tried the commands and get a segmentation fault like below:
Found 0 possible wallets
Found 0 possible encrypted keys
Found 0 possible unencrypted keys
zsh: segmentation fault python2.7 pywallet.py --recover --recov_device='./thumb7.img'