I like her a lot what should I do?

well there is this girl I and she is a freshman like me. the only cl we have together in homeroom which usually only last about 15 min. but this week we had to do testing so we were in there for like 2 hours. Her and I started talking a lot more and we became good friends. she single and I've been procrastinating to ask her out but I never know when to do it well I texted her and ask who she liked and she just responded with someone, I asked if I know him and she said no, and I asked why she couldn't tell me and she just said because.I told her I wasn't going to tell anyone and that she can trust me but she just said no. well its been a day and she still hasn't texted me back. I think she likes someone else so I'm kinda afraid to ask her out when I'm almost positive it will end in rejection. I don't really care if she likes someone else but I just wanna know who the person is.what should I do??