Oh.
If she is feeling sad
-Leave her alone (if she wants you to)
Or
-Stay with her (if she wants you to)
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If she is happy
-Make a note of what made her happy and if you can't figure out what did it's probably you that made her happy.
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If she is hurt
-Help her wounds heal ex. Broken arm you could help her write or help her eat or even bring her flowers and snacks or other things she likes.
Maybe the only comfort she needs is you.
I can't really tell you how to comfort her exactly because people are different.
It's up to you to find out what makes her happy and what makes her sad.