A similar situation happened to me with Splatoon, where I ended up losing all my data.
In that scenario, I took a breather, and just start all over.
Fortunately for me, I've pretty much gotten back to where I was now.
"Just for comparison Uncharted 4 was 20x bigger than Splatoon 2. This shows the huge difference between Sony's first-party games and Nintendo's first-party games."