In my opinion as a pathologist who has worked with brain injuries:
Some memory will return. Some permanent damage was prob. done.
You can compensate with writing things down
Keep a small writing pad with you and make lists of things to do, etc.
Keep dates/appointments on a calendar to check ea. day. Make lists.
If you are away w/o paper leave voice message on your phone to remind you.
There is some research about taking cod liver + flax seed oil ea. day.
Healthy diet and exercise stimulate the brain.
Reduce or better yet quit coffee, sodas, cigarettes that can increase anxiety.
Try meditation or yoga. Have faith that you will improve. Have hope that today you will lay your head on the pillow after a sober day.