Do not panic
First of all, try not to panic–the more you panic, the more you lose focus on your mission to find the lost person.
Contact their loved ones
You want to contact all of the people they have contact on a daily basis and find out if they know where this person is. Contact parents, significant others, close friends, and family. Tell all of them to contact you if they find out where the missing person is.
Submit a person missing to the police
Inform the police of all the information about the missing person: height, age, illnesses, gender, clothes on, date of birth, hair color, eye color, any distinguishing features (piercings, tattoos, etc.). It will help to provide them with a recent photo of the missing person.
Use the Internet
Share the information and a photo of the person online via a social media website such as: Twitter, Facebook, Myspace.
Put posters and flyers up of the missing person with all the information about them, their disappearance, and their appearance. Include a photo.
Do not give up
Do not stop the search until you are certain that the person is completely gone. Hopefully all goes well and your loved one is found.