At the special education office, ask to have an evaluation meeting to discuss ways your son can continue his education. Be sure to take all of his records, including test scores, to the meeting. The district may have a special program or alternative school that can help your child.
If you are not happy with the recommendations that the school district makes or have not worked well with the special education department previously, you should seek help from a family counselor or psychologist. Besides making specific suggestions about schooling, this individual could also provide the counseling that your son may require in order to re-enter school. You should choose an individual who has previous experience working with children with LD (learning disabilities)and ADHD (attention deficit disorder with hyperactivity).
The GED test may not be a good alternative for your son as many states have 18 as the minimum age requirement. You might want to investigate if your state has a proficiency test that is the equivalent of a high school diploma. Both of these tests are difficult.
Unfortunately, there are many others who have experienced a similar set of problems. You can find solid information on ways to help your child by visiting these websites: National Center for Learning Disabilities, Coordinated Campaign for Learning Disabilities, Children and Adults with Attention Deficit/Hyperactivity Disorder, and National Attention Deficit Disorder Association.