Updating with answer:
Ok, so digging a little I found out that my map was really corrupted and won’t load anymore. BUT in the …/projects/“yourprojectname”/saved/backup folder, there is an .UMAP file. Just duplicate this file and write the SAME NAME of your bugged level map. Now Ctrl+X this file, go to your project’s Content folder, navigate to where your level map is (mine was at FirstPersonBP/maps), delete the level map and just paste the file from the backup folder. This should load your last saved map.