Big question Undertale plz help omg

Major Spoilers for Genocide
Only answer if you dare
So I did genocide and killed Sans, Asgore, and Flowey, and I "destroyed the world" for Chara.
Now it's just a black screen when I reopen the game
Why is this
And how do I fix it
I know how to hack through file0 if I need to do that just say
Thanks