well this should be a good learning sharing moment. zillions of questions come to mind.

1. Why does she not care?

what does she care about?

animals flowers birds fairy tales?

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I'd start with bedding -- try to find something that combines the two target colors. Then you could use a less saturated version of one of them for the walls. Probably you'll want a white headboard, so you're not too locked down, but you could paint, say, her chest of drawers one of the colors, with a lamp the other, etc.

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I agree with acm, start with bedding. You could take a color for the walls and another color for the ceiling. Or do alternating walls in the same color. I feel a kids/teen room have different decorating rules than most rooms. Are you working with existing furniture or buying new? What is the flooring? Think about an area rug even if there is already carpet, i find it a good way to add some fun color to a kids room. If she likes books, do you have space for a beanbag chair reading corner?

Obviously, the best thing would be for her to be more involved, but if she isn't interested, there's not much you can do.

You could do the green about 2/3 of the way up the walls then the blue on the top 1/3 so it was like land and sky (I suppose you could flip the proportions so there is more sky than land, too). My room was painted similar when I was a preteen and I had little animal and butterfly decals that I could move around on the walls. Then find bedding in the blue and get her a nice, big bookshelf and desk that aren't necessarily those colors. Maybe a light wooden or white bookshelf and a glass/acrylic desk. It's good to have some solid neutral colors, especially if she ever decides not to love these colors anymore.

Another thing I loved at that age was my butterfly chair. I think it was actually those two colors and I sat and read in it all the time. They're really easy to make if you can sew, so you could make it any color she wanted.

Is there anything specific she likes besides books? Maybe some specific books?

I like the idea of painting the ceiling one color and the walls the other.

In the first three rooms below, replace pink/orange accents with green.

Maybe she has given you direction! I am very kind to people when they don't give me a lot of details. Cautious.. friendly.. patient. I honestly would paint two canvases from micheals in those two colors and start there! Hang the green low or lean up against wall. Place the bed color up above the head board area or above nightstand. Buy shams in the color only.. wait for her to get inspired again and add more!

Oh., once you find the furniture or the accents - etc.. then get serious about painting walls and furniture.. I probably would not though.. you would have to show me the room. That color all over.. personally.. it would have to go earthy and black metals.. or brass.. antique pictures.. like in France. Those are spring feelings. Spring gets white, colors come in the room through other features like bedding.

i would work very hard on at least what she likes in the world. blue and green butterflys?