How are memories stored and retrieved?
There are so many different ways.
At the neuronal level we have thus far identified three major pathways for direct storage of memories – loosely dubbed short medium and long term memory.
I suspect that we will find more.
The potentiation of connections between neurons at the synaptic level is amazingly complex, with so may different chemically mediated emotionally connected systems – we have identified about 60 thus far, I suspect we will find many more at ever more subtle levels.
Motor memory is a very different thing from sensory memory, or abstract memory, and things like song and dance are a mixture of the two.
Even our eyes and ears and other sense organs have their own sorts of memory and learning, as do each of the processing systems through which that information passes before it gets to our awareness.
Every one of our cells has memory, and relationships, with the cells around it and the wider systems of the body.
So many levels of interconnected systems, almost all of them with various levels and types of memory!
And they are all connected in various complex ways.
Then there are all the external forms of memory, the writing, drawing, pictures, movies, and all the many forms of symbology that carry encoded information (memory in a sense) could fill volumes today.
It is not a subject for a post, but for a lifetime of study.