You only just got her, though, didn't you? Give her a little time more to settle in, and then she'll probably take some food. Just keep offering it to her. It may take a while for her to adjust and be willing to eat.
Some are just more sensitive than others. I've had some take over a week before they'd eat. Some were eating immediately when they got home. Each Betta is different.
I wouldn't worry about her yet. She can in fact go without food for considerably longer than a mammal without any ill effects. If, in a week, she still isn't eating, THEN you can assume she doesn't like what you're giving her. But, for the time being, I really believe that she's just adjusting to living with you. Some have a REALLY hard time adjusting to all the stress of being shipped, kept in a store, bought, brought home, and put in a new tank.
try to use a toothpick and moved the food across the surface to simulate live food. This only works if you feed one pellet at a time, which I think is the best way to feed a picky betta.
Yep, my vt only tends to eat food that wiggles. So I feed him live moths, brineshrimp etc. Although he'll eat flakes. My new guy will only eat food that sinks in front of his face.
Have you tried giving her peas?
My little Liza would eat nothing for 12 days.
I tried several kinds of pellets, brine shrimp, flakes, daphnia, freeze dried blood worms - you name it, I tried it.
Eventually one day she ate a pea.
And then she started eating frozen blood worms.
To this day, all she will eat is bloodworms and peas.
I do have to feed them to her off a spoon though, or she wont' eat them.