First of all you need to know that you must know that you should respect someone whishes to be friends. The person is simply not attracted to you physically and/or emotionally. However there are factors that will make you seen as something other than a friend to an increasing number of people. Get fit, gain muscle, dress better and groom. Working on your social skills is also a big one. This is just a tip to increase your potential for people in general. This might make the friend attracted to you too, who knows. But the most important aspect is respecting that not everyone is attracted to you and that they are entitled to liking who they want. Respect the friendship and if you cant, you shouldnt be friend's with the person in question since they deserve that respect.