Board Thread:LotR Mod Technical Support/@comment-29740540-20190802074437/@comment-25612015-20190813220121

For saves I don't know, but for a multiplayer server, the level.dat gets recreated automatically.

And yes, this file is necessary to interpret your region files as it gives the correspondance between Minecraft names and IDs for all your blocks & items.

I would also delete level.dat, level.dat_mcr and level.dat_old.

Alternatively, you could create a new world and just replace all the region files inside with yours.