I'm sorry, but I can't know enough facts to really tell you anything helpful. If they aren't married then you have to try to come up with some legal reason why she might be entitled to part of his 401k. There or may not may be an argument, depending on the situation, but if he isn't cooperative litigation would be required to enforce a claim. If she even has one.
If he didn't contribute to a 401k while they were married (if they were married) there probably isn't much you can do about that. There are things I would like my husband to do but I sure can't make him do what I want.
CLearly there is a lot more to this story, that is why I said that your friend should have someone here in the US to help her out. Anything I might say really won't be of any practical help.
Please note that no one on this forum can give you legal advice on these issues.