Believe that there are other people. Sometimes we have feelings for someone are not returned. This is okay. You shouldn't feel like it's the end of the world or that there's no one else for you. There are an awful lot of people on this planet, after all. If someone doesn't return your feelings you should understand that it wasn't meant to be and that you wouldn't have been all that happy together. You'll find someone else before you know it and wonder why you ever felt upset in the first place.
Don’t try to be someone you are not to get someone to fall in love with you. Make sure that the person you decide to be with is compatible with you as you are