The map not opening in a newer version of the world editor doesn't mean it's corrupted, it's probably just because the editor has become unstable in recent patches. You should still be able to open your map with an MPQ editor and extract the war3map.wtg and war3map.wct files, in which trigger data is stored.
If the map really is corrupted though, it depends. I've seen some corrupted maps that completely lost all data and others that still had some files that could be recovered. In this case you might want to post your map, then I could check for you if any files can be recovered.