Change these to DWG and then try to open them with AutoCAD. Go to your OPTIONS window and look in the FILES tab for the AUTOMATIC SAVE FILE LOCATION and go to that folder on the computer (using Windows Explorer, not AutoCAD) and look for the files with AC$ and BAK extensions. How do I recover an unsaved AutoCAD file in 2018? In the Mac OS, this can be found under the Application tab in Preferences. The location of autosave files in the Windows operating system can be determined by going to the Files tab in the Options dialog box and inspecting the Automatic Save File Location folder in the hierarchy, or by using the SAVEFILEPATH variable. Which layer Cannot be deleted in AutoCAD?.Which file type is AutoCAD backup file?.How do I convert AutoCAD autosave to DWG?.How do I restore a previous version of an AutoCAD file?.How do I recover an unsaved AutoCAD file 2016?.How do I recover an unsaved AutoCAD file in 2018?.