If a girl says hi to you and you did not respond, what should I do?

this girl is a friend of mine for sometime. she is a shy girl in my opinion and usually says hi to me when we see each other. I have liked her more than as a friend then come one time that she said hi to me, and I did not respond to it. I don't know if she likes me or not but after that incident, she doesn't say hi to me anymore. I hope we can still be friends. Does she like me? Is she mad at me? what should I do?

well I could not really tell if she liked me or not. she is friendly with all her friends, be it girls or guys.
the only thing that makes me think she also likes me is when I was with her friends and it was already late night when she came by our room and her friends teased her "you are waiting for him". After that she exit the room quietly.