If you are speaking with her, read up a bit on reflective listening.

For example: if she says "I have no friends."

An unhelpful response is: "Of course you have friends, for one thing, I am your friend." By this response you show her that you cannot understand how she feels and you thereby reinforce the idea that she is right to feel alone. You also invalidate and dismiss her by contradicting her.

The issue is not the facts of the situation, the issue is her feelings about the situation.

A helpful response is: "You feel so alone right now."

By this response you show her that you do understand her, you validate her, you show her that she can actually connect with someone.