I believe my sister is manic depressive, but she is breaking ties with the family, and won't ever believe she has a problem. How would I go about getting her committed to get this problem taken care of? She has all/almost all the symptoms associated with manic depression, I just want to get help for her, but it is getting hard for anyone to beable to talk to her. Please help

You can't get someone who denies they have a problem help.
Even if you could they would not benefit from the help since they do not see a problem.
Most likely she gets on the defensive and feels everybody that insists she has a problem are the ones with the problem. Like the saying "I'm not crazy, its everybody around me that is crazy''.

When she does talk to you and she is in one of her moods you could try making comments like ''I'd rather discuss this when you are in a better frame of mind about this''. But pretty much anything you say can and will be held against you most likely.

It is hard to get someone committed, if they will not just sign thierself in some place.

If they are a danger to thierself and it can be proved you may get them in for evaluation.

If you have several family members ( differs by state) sometimes they go before the judge to ask for a commitment