My dad could not operate normal music players. But he could use the music player that I made for him, because it operates like a familiar two-knob radio. I was inspired to make this by the documentary Alive Inside which shows the profound joy felt by some people with dementia feel when listening to their favorite music. Here is my Dad using an early prototype:
I went through several revisions, making it simpler each time. Everything I did (e.g. software, wood case design) is open source. So it’s now pretty easy to build one. You can order the parts online, including the pre-cut pieces for the case. No soldering required. Details below.