I can't load Minecraft singleplayer

So...

I was making my school mod, and then out of nowhere i had that Error in loading datapacks. So i updated the whole project, used some of the fixes that moderators wrota, but the, out of nowhere, i can't click on the singleplayer button! I deleted every world before, because i thought that it had some problems with my world, when i was solving that datapack problem. But now, when i click on singleplayer button, it just says saving world and the whole minecraft crashes.

If someone has a solution, i would be so happy :) I spent working on that mod several hours, so yea.

also, i can post the console, if someone would look into that