I am not exactly sure what you mean by not being able to visualize, When you visualize you are just using your imagination. It is not really like seeing it like in a dream or in person. Can you recall a place and remember what it looked like, felt like etc? If so you are visualizing. Visualizing has worked for me, though it has been a long time since it has, it has only worked once for me though, I kept visualizing the beach, the waves crashing on the shore, feeling the sun etc. I woke up in a dream under a pier at the beach, it was awesome and realer than real, but it hasn't worked since.