We would recommend you consult the Finding A Missing Loved One page on NAMI’s website for guidance on where to begin and options available for locating a loved one who has gone missing.
Additionally, the website of How Stuff Works provides information on their What to Do if a Loved One Goes Missing page that you may find very helpful. This resource explains the role of law enforcement, the differences between finding missing children vs. adults, and ways you and your family can personally advocate to find a missing loved one through social media platforms, flyers, and working with a private investigator.
You may also wish to consult the website of National Missing and Unidentified Persons System (NAMUS), an organization that maintains a national database on all missing persons and provides free investigative support. If your loved one is under the age of 20, after filing a police report, you may wish to contact the National Center for Missing & Exploited Children (NCMEC) at (800) THE-LOST to open up a case.
For persons missing 6+ months, the Salvation Army provides an international service to help facilitate successful reunions between family members who have lost contact with each other. Searches are conducted utilizing a variety of methods, including government offices, credit institutions, social service agencies and law-enforcement personnel. Contact SA’s Missing Persons Regional Office (Eastern, Central, Southern). Find correct region contact information by searching “Salvation Army missing persons locator.”