Most likely the map is gone for good. If you're lucky it'll re-appear if and when the assets.tdx is re-built. (I'm not telling you to attempt re-build.) If you know of a distinctive file-name from within the map you could try a text-search.
I've deleted maps from within TRS who came back after database re-build, also deleted assets plus corrected assets who were overwritten by old ones packed with errors. (I hate it when this happens.)
Where these assets been hiding and how on earth assets.tdx can find them again when it's starting from scratch - I sure would like to know.