My understanding, and I can't remember [ha] where I read this (maybe
Under the Influence?), is that events that happened when your memory was "blacked out" by drinking are simply not stored in the brain. There's no way to access events that happened then, because your brain did not put them in memory in the first place.
That said, I could be remembering that wrong!
My memory has never been great, but it was complete rubbish when I was drinking every day. It seems to be slowly recovering in some areas now. Also, not being in denial anymore has made me remember some things I had forgotten about for years... not necessarily pleasant ones!