After deleting the “DIM-1” file to reset the nether the “DIM-1” file doesn’t appear in files. Also you can’t get into the nether in game(you get stuck in an animation)
Could be that some mod is having a hard time with the dimension missing, do you have any backups?
If not you should be able to generate a world with the same seed, then copy in it’s DIM-1 as a replacement
I do have some backups but i dont want to lose 5 days of progress, also i reset the nether after deleting the mod incendium cause it was causing too much lag