Backup files are generated automatically by DIALux every time when saving.
The backup file is located at the same folder as the original file and equally named, but with the additional extension "BAK". The typical structure is "projectname.evo.bak".
You can convert backup files to project files by yourself. The backup file needs to be renamed from "projectname.evo.bak" to "projectname 1.evo".
After renaming it, the file should be readable as every other DIALux project file.