You will have to access AppData\.minecraft\saves and find the folder of the corrupted world and make  a copy of that in a new folder. Then, start Minecraft, create a new world, then save and close Minecraft. Then, cut the files:

level.dat
level.dat_old
level.dat_mcr
session.lock

and replace the ones in the copy of the corrupted world save file you made. Then, restart Minecrat and rename the world "back" to what the actual corrupted world was named, but your inventory and some information about mods will be lost, but it can be restored with an NBT editor by copying the content of the root node from the file user.dat , note that user to be substituted with your IGN, to the node "Player" in level.dat