With "Regenerate BH"? Will it only recreate the lost stadium? Because I have made lots of other edits and changes, like adding stadiums, kits, teams, changing lineups and names and all that, I don't want to lose all that work.^ Search for all files with the ID 149 inside your stadium, fx and crowdplacement folders (inside sceneassets) and delete them. Regenerate with the tool of your choice (ie: CM16) and your stadium will be back.
Sorry if the question is dumb. I really know nothing about regenerating files.