Adoption searches are generally very difficult due to privacy laws, designed to protect the identify of the birth mother. In most states, when a mother puts her kid up for adoption, because he or she was born out of wedlock, teen pregnancy, or whatever reason, she has the legal right to demand her privacy be protected.
All’s not lost. Depending on the state, with a bit of legwork, state public records may be of some help and most have some type of assistance available. If you wish to investigate what might be available to you.
The Web has fortunately been a Godsent for streamlining the reunion of many an adoptee and their birth parents. There are lots of adoption related search sites both national and international you can find via Google search. These sites generally function by keeping registrations of adoptees & birth parents where each may meet online and post a messages about themselves. Unfortunately this method is only successful if both people are searching for each other and usually find each other “by accident.” Some people turn to private investigators for help. Where a person is on the Federal Witness Protection Program, finding them is essentially impossible, until they are released from the program.
adoptionregistry.com is a good place to begin.