Maybe you should try a toy that you can hide treats in. There are balls that will hold food and treats, if you can get her to play with that you might be able to get her to play fetch. Maybe just try something simple, she may have a preference you don't know about. Like, some dogs go nuts over plastic bottles, and some don't care. Try cheap stuff like water bottles and sticks before you buy her tons of toys just to find out she'll never use any of them. Maybe give her an old stuffed animal to chew on? My friend's dog doesn't like to play fetch for very long, and he's not very good with tug of war, but he does like stuffed animal toys. Our dog sometimes doesn't like a toy if he's never seen it before. I got him a bunch of toys when we got him, he didn't like some of them at first, but if I play with them anyway he learns to love them. He didn't like his Kong at first, I'd give it to him and he'd just look at me like "what's that? that's not a ball!" and if I threw it he'd just go get another toy to play with. Now he loves playing with it

If she won't play then maybe she just doesn't like playing, some dogs just don't, but they're still fun

Good luck getting her to play!