Hi Henrik, welcome to the community. Where in the world are you joining us from? So it sounds like you're saying your visual imagination flickered between 3D and 2D until it wasn't there anymore. Is that correct? Or can you still visualize in 2D? Also, do you remember the things you last saw? It sounds like you may have had a similar experience to Rebecca Brady. Check out her story about losing her mind's eye. According to the available research, it appears the majority of experiences are congenital aphantasia (since birth), while acquired aphantasia could be related to head injury, stroke, psychological trauma, or other events resulting in brain lesions or chemical imbalances. However, there hasn't yet been a ton of research in this area, much of the existing information is anecdotal stories like your own. Here is another discussion with a few others about developing aphantasia later in life.