How can I fix this?

So my Girlfriend is kinda changed since past 4 days and she isn't willing to tell me what's the Problem too... All she says is "I have no Expectations" "Do whatever you want" And I wanna know what did I do, I want to fix things up and then she says "Everything is Fixed" "There's no Problem to solve"

Yesterday too I called her and whole 3 hours went like me asking "Please tell me what happened?" And she answering "Nothing has happened"

Can you tell me how can I solve this? Sometimes I Thinks she is Forcefully with me... I want to make her feel wanted...