Is this really your friend's account or you bought a computer and you found a wallet on it?

Most probably the previous user of this computer might have stored their password somewhere on the computer itself. That might help you. You might have to use some services to analyze all deleted files on this computer to find some clues like txt files with email or passwords.

If that's not the case, it'd be really helpful what your friend might think the password is. Like if he thinks that it is a combination of some words or it is 10-16 characters long of there is a particular set of characters in the password somewhere or something. If nothing else, the only case is to try all possible passwords till 12-13 characters and if it doesn't work then we can lose all our hopes until our computational tech is so adv to crack that. It might take some decades.

You can mail me or skype me at milli2311ravi.000@gmail.com and we can discuss more and I think I might help you somehow.