If you were scheduled to appear before an immigration judge and did not go, you failed to attend a removal hearing and were almost certainly ordered removed/deported in your absence. If you are still present in the US, it is sometimes possible to get the case re-opened, the removal order vacated, and a voluntary departure order entered, but this is very difficult to accomplish. Once you are outside the US, it may be possible to fight this ground of inadmissibility if there was some extraordinary situation that prevented you from being able to attend the hearing. Simply being a minor at the time of the hearing does not automatically erase this problem, though it may be an argument worth making. Please note that if the government sent the hearing notice to the wrong address, it is your burden to prove that you provided them with the correct address. Immigration hearing notices do not get forwarded with other forwarded mail.