My sister has been lonely for the past 37 years she doesn't want to socialise or talk to anyone, is there anything I could do to help her?

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Take it slowly and carefully. Withhold judgment and just be happy they’re talking to you at all. Slowly introduce her to more and more things, if she says no to one thing, just suggest something else the next time you see her.

She’ll come out of her shell eventually if you keep at it.