If there’s a way for you to talk to her in person, then do it so things can become clear for you.
There are many possible reasons why she suddenly disappeared. She might not be interested anymore, she might have met someone else, or there could be other reasons like she lost her phone or something unexpected happened to her.
That’s why the best thing to do is, if there’s any way to see or reach her, try to do it so you can get clarity.