That sounds incredibly sad and frustrating. I can't imagine what it's like to suddenly lose that ability, being so dependent on it.
Indeed many of my childhood memories are mostly sequences of pictures, the emotional content kind of "floats" on the imagery. It must be very frustrating, being forced to reinvent how you experience your inner life and memories.
Edit, after reading some more comments: are you musically inclined? Did your ability to hear melodies in your "inner ear" suffer similarly?
It sucks, but that's life - there are worse things and life is still plenty enjoyable. In addition, I lost my sense of smell/taste completely and that was much worse to be honest (but still, you learn to live without and focus on what's good). If I had to choose between the two, I'd choose being able to smell/taste any day. Funnily enough not because of food, but actually because of the added experience you get when walking in nature or other places - smell has so much to do with experiencing things, but you never consider it until it's gone. Luckily it came back, even though it's been 2.5 years now and it's still only 80% normal (but 80% is quite good!).
As you mention, the most sad part about it is actually the childhood memories, but I still have the memories of course, they're just a bit more "facts based" than re-living experiences.
Luckily, I didn't lose my inner ear or even inner monologue like in another reported case [0]. I do play instruments, so I guess I was/is musically inclined to some degree. I still have ability to imagine music exactly like I would hear it, unlike a friend with aphantasia who can't.
Another interesting detail is that I regained the ability before losing it again (Covid re-infection), and during this time of recovery I could gradually see grey, blurry images that got better and better. It's like the image generator in my head didn't have capacity to create full blown images, but only low res ones. Which makes me believe that in my case the "image generator" was damaged as I couldn't even dream in pictures, while for most people with aphantasia that's not the case, as they can dream normally.
On the bright side, I don't get horrible, lifelike images popping up in my head anytime I hear about something disturbing. Not that that was a big problem, but it's something you notice. It makes me believe that people with aphantasia might be better at coping with disturbing events, as they don't have to re-live the experience visually. But that's just a theory.
Smell is super tied to memory so that could be the cause of your imagery issues. I almost completely lose my sense of smell due to concussions in early adulthood but occasionally it randomly comes back (briefly) in full force. Anything I smell at that time triggers very visual memories in my head from childhood.
Neurology is still such a black box medically. Did you by any chance have a brain MRI at any point? If yes, and your willing to share, what portion of the brain was impacted? If more than one, has there been diagnostically visible change between them? Did you get any treatment? I can be reached at first at full tod moc if you prefer.
I've had a brain MRI to rule out other causes (tumors etc), but it was clean. I don't think they looked specifically for tiny damages to areas (if that's possible), but I'm not sure to be honest as I only got answer that there were no signs of disease.
Well maybe it's a good thing. You live in the present instead of an imaginary past. The past is gone no matter how much your mind tries to come up with images. The memories no longer have any existential significance apart from causing you trauma, generating false sense of pride, etc. Helps you to do and try new things instead of relying on a past you once lived and no longer exists.
I do tend to think I live a bit more in the present because of aphantasia. However, I also do have an experiential memory. It's not great, and largely not visual, and to the degree there are any visual elements they're pretty useless, like burnt fragments of a Polaroid. I think you're kinda having a hard time imagining this condition.
Indeed many of my childhood memories are mostly sequences of pictures, the emotional content kind of "floats" on the imagery. It must be very frustrating, being forced to reinvent how you experience your inner life and memories.
Edit, after reading some more comments: are you musically inclined? Did your ability to hear melodies in your "inner ear" suffer similarly?