It's like you were doing something then absolutely nothing.
The crash that broke my neck and back; it was seeing an idiot double parked in the road, hearing the car about to pass me, waiting, matching speed to ensure I wouldn't get hit by some idiot from behind and slipping into the stream behind a Jeep Grand Cherokee. I remember the passenger side taillight. It wasn't the brake lights coming on or anything, just the car passing and my focus sliding across in that moment, then I'm totally blank.
I've had anesthesia before. It was a blank minded state even stronger than anesthesia. I came to when a major nerve for my lip was cut by the removal of the last large piece of glass from my chin. That was 3 hours later. I was in tremendous pain, already heavily drugged, and my lip didn't even register as more than a mild poke by comparison to what my back felt like right between my shoulder blades. It felt like I had a long sword through my back. Most of my major damage was around my skull and neck, but that spot in my back is all that I have ever felt and still feel. I had major damage to C1 and the base of my skull. If I had not lost consciousness and tried to move before the swelling could hold most of the stuff in place, I was told it probably would have killed me. I think I was pretty close to death in that one. Many times I wish I had died then. If I had died. I would have had a beautiful February morning, feeling awesome, focused, ready to finish putting together my inventory proposals for the new shop we were opening up.
If there was something else to talk about, I wouldn't hesitate to mention it and tell you all about it. There simply wasn't anything at all. Even some element of my subconscious that I am aware of with sleep was missing. Waking up like that feels like I died when I look back. That is because I had to give up everything, all of my interests and motivations were forced to change due to my physical limitations.
So what does it feel like? It feels like nothing. It feels like "how the fuck did I get here, and what the fuck happened," even when you're unable to think straight or say very much.