I can recommend Hashcat, used it myself for cracking bitcoin wallet using multiple GPUs. Great tool if you forget your password and it works with so many applications/file formats.
You need the entire encrypted wallet so you can extract the password hash from it even then you need to know your password to the point of only 3-4 variable chars to be able to effectively crack it or use a pretty simple password that is either moderately short Witt a small key space or is in a dictionary.
Cracking the private key of a bitcoin address is beyond todays computing power.
I think the scenario here is that he had an encrypted wallet file that he didn't have the password for. In that case, cracking it is only as hard as the password (in other words, relatively easy if he remembers the enough about his password).