What will you do if it was you?(please help)?

Perhaps she was depressed (needing help) that time when she didn't greet you for 1 week. Don't ignore that girl because it would hurt her feelings, just go for it. Do not be a loner or isolationist because you would regret it in the end. I cannot say that girl likes you because she might be only wanted to be friend with you or observing you (weird). You'll get it soon when your growing up...