Advice on how to help close friend suffering from intense burnout?

Hi, I (14f) have a very close friend suffering from a mix of neurodivergent burnout and depression for the past few months.

She’s had to cancel lots of things she was really excited for this summer and hardly ever steps out of her house anymore… and she has been talking to me and our friends less and less.

I just would like some advice on how I can help her feel better. I have asked her this but she says she doesn’t know.

I’m just kinda scared. She’s a really awesome person and I don’t want her to do anything stupid.

EDIT: wording