Ruminate on exactly why you have a crush on this person. There is an important distinction between the person you have a crush on and the reasons why you have that crush. You may be going through a difficult time with a parent and you may be redirecting and misplacing your parental problems on this person.
Talk to people that know the person you have the crush on. This person may not be as perfect as you make them out to be. All people have flaws and realizing this fact about another may give you proper perspective and help you deal with the crush.
Meet other people and open yourself up to others. Taking your mind off the crush or finding other people to fill the void left by the crush can help you in dealing with it. Make a list of your favorite qualities in the crush and start looking for someone new with many of those same qualities.
Speak to the person you have a crush on them and tell them about it. Holding a crush in can cause you anxiety because your can only imagine how this person feels about you. Talking to them will help you move on with your life.
Tell your close friends about the crush. Conversing with others you trust helps you get another person's perspective about the crush, and how to deal with it. Friends not only offer perspective, but support as well.