Summarize:

In most cases, romantic rejection is not a criticism of your character. If a girl decides she doesn't want to date you, it doesn't mean she dislikes you or even finds you unattractive. Though every instance of rejection is different, the common thread is that "you" are not rejected. Rather, your request to date is. After the rejection, don’t be afraid to feel any emotions that come your way. Sadness, anger, fear, and similar feelings are all natural parts of rejection, and working through them now will make it far easier to move on in the future.  Don’t be afraid to cry or scream when you're alone. If you can, talk through your feelings with a close friend, family member, or therapist. Sharing your emotions with a supportive, understanding person can make a huge difference in your mental well-being. Though returning to the rejection may hurt, doing so after grieving can help you better understand what happened and gain some closure. If you believe your crush said no because she dislikes something about you, think about whether it is something you should change or if it is a simple matter of preference. In addition, remember that there are plenty of reasons she might have said no that aren’t related to you, such as:  She is too busy to date. She has a different sexual orientation than you. She is working through personal or emotional issues. She already has a significant other. She has a crush on someone else. She enjoys being single. If your crush is someone you see a lot, it's normal to experience some awkwardness after a rejection. Over time, you and your crush’s nerves will cool down and your normal friendship can resume. Until then, try to be as kind, friendly, and polite to your crush as you can.  Say "hi" when you see her. Smile and ask how she is if you're nearby. Just treat her like a friend and eventually you'll feel better around one another.
Remember that rejection is not a personal attack. Give yourself time to grieve. Think about why she said no. Be kind to your crush even if things feel awkward.