When my kids started up, I picked me up some sheet music I wanted to play. Knowing now how to "study", it took some
real practice (something I never did before), but I quickly got back to where I was. In some aspects, I'd say I was better.
I guess it depends on how far you got when you quit. I got far enough that I was comfortable with music theory and reading music, I just didn't have much talent. So it was just a matter of willpower to learn the songs I wanted too.
It was rewarding. I even wrote a song, something I could never do when I was in lessons.