Now this is what can be described as a real tricky situation. It is easy to find a lost person than a person who doesn't want to be found. If he/she doesn't want to be found then it means that the person is deliberately out of sight or living incognito. So this makes it easier to make find such persons who have no desire to be found. But still the advent of science and technology can assist you in tracing such people. You can also take help from the police authorities or private detectives to trace such a person by providing them with whatever details you have about the person you want to find. Otherwise there are sites like PEOPLEFINDUSA.com which will help you to find such people for a nominal charge. You will have to supply whatever information you have about the person and based on that this site would try and rack down this person. But the results may depend on the information that you can provide i.e. Suppose you know only the name then it would be harder to trace the person than if you have his social security number, his old address and other such details.