I think my sister might be depressed

So my sis, has IG. She has these posts of her "crying", & saying shes depressed.She also has these posts of saying no one likes.Also she is always in her room.

What should I do? sorry thats much doing this from my phone

What is IG?

The simplest thing to do would just be to talk to her. Maybe she would appreciate it if you reached out to her. Or if she would feel comfortable with a neutral person, maybe see if she would be willing to talk to a doctor, therapist or school counselor (if she's in that age range) about her problems.

Sometimes people just need someone to talk to and have someone hear what they're going through.