after amnesia or a concussion, do you find your memory rear legs?

Sometimes yes, sometimes no. I believe that a lot of pro-sports players will forever lose a segment of memory of the event that caused a concussion. Amnesia can also be due to stress / shock - so you may capture that memory back when you settlement with the fearfulness that is blocking the memory.
So: answer = it depends on what cause the damage, and how severe the violate is, and how good your body is at fixing itself.
it depends on how substantial the disfavour is.
maybe, sometimes never
Usually, yes. Amnesia can ultimate a long time or a short while, but generally go away after a period. That's across the world, not always.
Amnesia is recurrently the result of a concussion, which is simply the brain hitting the inside of the skull. This necessarily produces at least a split second of blackout, and often some loss of memory, which may be permanent- esp. as regard short-term memory from that time.
I was within a car luck in 2000, and be out for about 20 minutes. When I awoke, I know my name, and I know I had crashed, but I didn't know where on earth I was, what time it be, or how I had gotten in that. It all come back in 30 seconds, though, and I remember everything almost the incident now. :)
Sometimes you do, sometimes you don't - it depends on how severe the lay waste to is, where the deface is, and a little bit on how lucky you are!
This is similar to all question involving neurology. Each case is different. Also, concussions may be associated beside amnesia, but they are wholly different conditions.
perchance, maybe not, depending on damages