What if I don't remember a memory?
Memory is a construct of one or more of these building blocks:
4. Smell (Olfactory)
5. Taste (Gustatory)
Most people think a memory is just a mental picture / movie, but not every memory has a visual aspect.
Some may just be a bodily feeling. Or a sound you hear. Or just a "knowing".
If you work on whatever you can work on, a memory may or may not pop-up.
Even if it doesn't, don't beat yourself up. Changes will still happen - as long as you persistently work on what you can.