Hi, I'd like to help you with your question.
I agree with you, it does sound like you may have sustained neurological damage when you were hit by your father. You were brutalized and traumatized by your parents. Damage that is physical and emotional can cause you to feel the way you describe.
The first step to take is seeing your doctor, if you have not already done so. Testing to determine if you have any brain damage or other physical effects from the abuse can rule out causes or give you an idea of how they are affecting you. There is a guideline in psychology to always rule out the physical before you consider the psychological. There are many physical problems that mimic emotional or psychological issues. Therefore, it would be a waste of time to treat a person in therapy without being sure that is what you are dealing with.That is why this is an important first step.
Once you are aware of what is physical and emotional, then pinpointing your symptoms and your issues is the next step. You mention having trouble in relationships, being withdrawn, and having problems at work. Although this is general, I will take a guess here and say you probably have Post Traumatic Stress or at least symptoms of it. You could also suffer from depression. I'm not sure if any of the therapists you saw mentioned these diagnosis to you but it is a possibility and needs to at least be ruled out.
Since you did not feel therapy worked for you, self help is an option. Sometimes, people can learn about their symptoms and find ways to get support through self talk, group therapy, support groups and talking with trusted friends and family. It is not a substitute in the cases of serious illnesses like Bipolar that need medication, but it helps in cases such as yours.
Here are some resources to help you:
Adult Children of Abusive Parents: A Healing Program for Those Who Have Been Physically, Sexually, or Emotionally Abused by Steven Farmer
Toxic Parents: Overcoming Their Hurtful Legacy and Reclaiming Your Life by Susan Forward and Craig Buck
An Adult Child's Guide to What's 'Normal' by John C. Friel Ph.D. and Linda D. Friel M.A.
Lifeskills for Adult Children by Ed.D. Janet G. Woititz and M.A. Alan Garner
Adult Children as Husbands, Wives, and Lovers: A Solutions Book by Steven Farmer
You can find these books at Amazon.com or your local library may have them for you.
The main focus should be dealing with the trauma you suffered. Children who suffer abuse such as yours can have a lifetime of effects. But reaching out for help, learning to trust, and helping yourself can all go a long way in helping you overcome your childhood trauma.
Let me know if I can help any further,